Latest Posts (20 found)

bye bye RTMP

In May 2010 we merged support for the RTMP protocol suite into curl, in our desire to support the world’s internet transfer protocols. The protocol is an example of the spirit of an earlier web: back when we still thought we would have different transfer protocols for different purposes. Before HTTP(S) truly became the one protocol that rules them all. RTMP was done by Adobe, used by Flash applications etc. Remember those? RTMP is an ugly proprietary protocol that simply was never used much in Open Source. The common Open Source implementation of this protocol is done in the rtmpdump project . In that project they produce a library, librtmp , which curl has been using all these years to handle the actual binary bits over the wire. Build curl to use librtmp and it can transfer RTMP:// URLs for you. In our constant pursuit to improve curl, to find spots that are badly tested and to identify areas that could be weak from a security and functionality stand-point, our support of RTMP was singled out. Here I would like to stress that I’m not suggesting that this is the only area in need of attention or improvement, but this was one of them. As I looked into the RTMP situation I realized that we had no (zero!) tests of our own that actually verify RTMP with curl. It could thus easily break when we refactor things. Something we do quite regularly. I mean refactor (but also breaking things). I then took a look upstream into the librtmp code and associated project to investigate what exactly we are leaning on here. What we implicitly tell our users they can use. I quickly discovered that the librtmp project does not have a single test either. They don’t even do releases since many years back, which means that most Linux distros have packaged up their code straight from their repositories. (The project insists that there is nothing to release, which seems contradictory.) Is there perhaps any librtmp tests perhaps in the pipe? There had not been a single commit done in the project within the last twelve months and when I asked one of their leading team members about the situation, I was made clear to me that there is no tests in the pipe for the foreseeable future either. In November 2025 I explicitly asked for RTMP users on the curl-library mailing list, and one person spoke up who uses it for testing. In the 2025 user survey, 2.2% of the respondents said they had used RTMP within the last year. The combination of few users and untested code is a recipe for pending removal from curl unless someone steps up and improves the situation. We therefor announced that we would remove RTMP support six months into the future unless someone cried out and stepped up to improve the RTMP situation. We repeated this we-are-doing-to-drop-RTMP message in every release note and release video done since then, to make sure we do our best to reach out to anyone actually still using RTMP and caring about it. If anyone would come out of the shadows now and beg for its return, we can always discuss it – but that will of course require work and adding test cases before it would be considered. Can we remove support for a protocol and still claim API and ABI backwards compatibility with a clean conscience? This is the first time in modern days we remove support for a URL scheme and we do this without bumping the SONAME. We do not consider this an incompatibility primarily because no one will notice . It is only a break if it actually breaks something. (RTMP in curl actually could be done using six separate URL schemes, all of which are no longer supported: rtmp rtmpe rtmps, rtmpt rtmpte rtmpts.) The offical number of URL schemes supported by curl is now down to 27: DICT, FILE, FTP, FTPS, GOPHER, GOPHERS, HTTP, HTTPS, IMAP, IMAPS, LDAP, LDAPS, MQTT, MQTTS, POP3, POP3S, RTSP, SCP, SFTP, SMB, SMBS, SMTP, SMTPS, TELNET, TFTP, WS and WSS. The commit that actually removed RTMP support has been merged. We had the protocol supported for almost sixteen years. The first curl release without RTMP support will be 8.20.0 planned to ship on April 29, 2026

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daniel.haxx.se 1 weeks ago

One hundred curl graphs

In the spring of 2020 I decided to finally do something about the lack of visualizations for how the curl project is performing, development wise. How does the line of code growth look like? How many command line options have we had over time and how many people have done more than 10 commits per year over time? I wanted to have something that visually would show me how the project is doing, from different angles, viewpoints and probes. In my mind it would be something like a complicated medical device monitoring a patient that a competent doctor could take a glance at and assess the state of the patient’s health and welfare. This patient is curl, and the doctors would be fellow developers like myself. GitHub offers some rudimentary graphs but I found (and still find) them far too limited. We also ran gitstats on the repository so there were some basic graphs to get ideas from. I did a look-around to see what existing frameworks and setups that existed that I should base this one, as I was convinced I would have to do quite some customizing myself. Nothing I saw was close enough to what I was looking for. I decided to make my own, at least for a start. I decided to generate static images for this, not add some JavaScript framework that I don’t know how to use to the website. Static daily images are excellent for both load speed and CDN caching. As we already deny running JavaScript on the site that saved me from having to work against that. SVG images are still vector based and should scale nicely. SVG is also a better format from a download size perspective, as PNG almost always generate much larger images for this kind of images. When this started, I imagined that it would be a small number of graphs mostly showing timelines with plots growing from lower left to upper right. It would turn out to be a little naive. I knew some basics about gnuplot from before as I had seen images and graphs generated by others in the past. Since gitstats already used it I decided to just dive in deeper and use this. To learn it. gnuplot is a 40 year old (!) command line tool that can generate advanced graphs and data visualizations. It is a powerful tool, which also means that not everything is simple to understand and use at once, but there is almost nothing in terms of graphs, plots and curves that it cannot handle in one way or another. I happened to meet Lee Phillips online who graciously gave me a PDF version of his book aptly named gnuplot . That really helped! I decided that for every graph I want to generate, I first gather and format the data with one script, then render an image in a separate independent step using gnuplot. It made it easy to work on them in separate steps and also subsequently tune them individually and to make it easy to view the data behind every graph if I ever think there’s a problem in one etc. It took me about about two weeks of on and off working in the background to get a first set of graphs visualizing curl development status. I then created the glue scripting necessary to add a first dashboard with the existing graphs to the curl website. Static HTML showing static SVG images. On March 20, 2020 the first version of the dashboard showed no less than twenty separate graphs. I refer to “a graph” as a separate image, possibly showing more than one plot/line/curve. That first dashboard version had twenty graphs using 23 individual plots. Since then, we display daily updated graphs there . All data used for populating the graphs is open and available, and I happily use whatever is available: Open and transparent as always. Every once in a while since then I get to think of something else in the project, the code, development, the git history, community, emails etc that could be fun or interesting to visualize and I add a graph or two more to the dashboard. Six years after its creation, the initial twenty images have grown to one hundred graphs including almost 300 individual plots. Most of them show something relevant, while a few of them are in the more silly and fun category. It’s a mix. The 100th graph was added on March 15, 2026 when I brought back the “vulnerable releases” graph (appearing on the site on March 16 for the first time). It shows the number of known vulnerabilities each past release has. I removed it previously because it became unreadable, but in this new edition I made it only show the label for every 4th release which makes it slightly less crowded than otherwise. vulnerabilities in releases This day we also introduce a new 8-column display mode. Many of the graphs are internal and curl specific of course. The scripts for this, and the entire dashboard, remain written specifically for curl and curl’s circumstances and data. They would need some massaging and tweaking in order to work for someone else. All the scripts are of course open and available for everyone. I used to also offer all the CSV files generated to render the graphs in an easy accessible form on the site, but this turned out to be work done for virtually no audience, so I removed that again. If you replace the .svg extension with .csv, you can still get most of the data – if you know. The graphs and illustrations are not only silly and fun. They also help us see development from different angles and views, and they help us draw conclusions or at least try to. As an established and old project that makes an effort to do right, some of what we learn from this curl data might be possible to learn from and use even in other projects. Maybe even use as basis when we decide what to do next. I personally have used these graphs in countless blog posts, Mastodon threads and public curl presentations. They help communicate curl development progress. On Mastodon I keep joking about me being a graphaholic and often when I have presented yet another graph added the collection, someone has asked the almost mandatory question: how about a graph over number of graphs on the dashboard? Early on I wrote up such a script as well, to immediately fulfill that request. On March 14 2026, I decided to add it it as a permanent graph on the dashboard. Graphs in the curl dashboard The next-level joke (although some would argue that this is not fun anymore) is then to ask me for a graph showing the number of graphs for graphs. As I aim to please, I have that as well. Although this is not on the dashboard: Number of graphs on the dashboard showing number of graphs on the dashboard More graphs I am certain I (we?) will add more graphs over time. If you have good ideas for what source code or development details we should and could illustrate, please let me know. The git repository: https://github.com/curl/stats/ Daily updated curl dashboard: https://curl.se/dashboard.html curl gitstats: https://curl.se/gitstats/ git repository (source, tags, etc) GitHub issues mailing list archives curl vulnerability data hackerone reports historic details from the curl past

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daniel.haxx.se 1 weeks ago

chicken nuget

Background: nuget.org is a Microsoft owned and run service that allows users to package software and upload it to nuget so that other users can download it. It is targeted for .Net developers but there is really no filter in what you can offer through their service. Three years ago I reported on how nuget was hosting and providing ancient, outdated and insecure curl packages. Random people download a curl tarball, build curl and then upload it to nuget, and nuget then offers those curl builds to the world – forever. To properly celebrate the three year anniversary of that blog post, I went back to nuget.org , entered curl into the search bar and took a look at the results. I immediately found at least seven different packages where people were providing severely outdated curl versions. The most popular of those, rmt_curl , reports that it has been downloaded almost 100,000 times over the years and is still downloaded almost 1,000 times/week the last few weeks. It is still happening . The packages I reported three years ago are gone, but now there is a new set of equally bad ones. No lessons learned. rmt_curl claims to provide curl 7.51.0, a version we shipped in November 2016. Right now it has 64 known vulnerabilities and we have done more than 9,000 documented bugfixes since then. No one in their right mind should ever download or use this version. Conclusion: the state of nuget is just as sad now as it was three years ago and this triggered another someone is wrong on the internet moments for me. I felt I should do my duty and tell them. Again. Surely they will act this time! Surely they think of the security of their users? The entire nuget concept is setup and destined to end up like this: random users on the internet put something together, upload it to nuget and then the rest of the world downloads and uses those things – trusting that whatever the description says is accurate and well-meaning. Maybe there are some additional security scans done in the background, but I don’t see how anyone can know that they don’t contain any backdoors, trojans or other nasty deliberate attacks. And whatever has been uploaded once seems to then be offered in perpetuity. Like three years ago I listed a bunch of severely outdated curl packages in my report. nuget says I can email them a report, but that just sent me a bounce back saying they don’t accept email reports anymore. (Sigh, and yes I reported that as a separate issue.) I was instead pointed over to the generic Microsoft security reporting page where there is not even any drop-down selection to use for “nuget” so I picked “.NET” instead when I submitted my report. Almost identically to three years ago, my report was closed within less than 48 hours. It’s not a nuget problem they say. Thank you again for submitting this report to the Microsoft Security Response Center (MSRC). After careful investigation, this case has been assessed as not a vulnerability and does not meet Microsoft’s bar for immediate servicing. None of these packages are Microsoft owned, you will need to reach out directly to the owners to get patched versions published. Developers are responsible for removing their own packages or updating the dependencies. In other words: they don’t think it’s nuget’s responsibility to keep the packages they host, secure and safe for their users. I should instead report these things individually to every outdated package provider, who if they cared, would have removed or updated these packages many years ago already. Also, that would imply a never-ending wack-a-mole game for me since people obviously keep doing this. I think I have better things to do in my life. In the cases I reported, the packages seem to be of the kind that once had the attention and energy by someone who kept them up-to-date with the curl releases for a while and then they stopped and since then the packages on nuget has just collected dust and gone stale. Still, apparently users keep finding and downloading them, even if maybe not at terribly high numbers. Thousands of fooled users per week is thousands too many. The uploading users are perfectly allowed to do this, legally, and nuget is perfectly allowed to host these packages as per the curl license. I don’t have a definite answer to what exactly nuget should do to address this problem once and for all, but as long as they allow packages uploaded nine years ago to still get downloaded today, it seems they are asking for this. They contribute and aid users getting tricked into downloading and using insecure software , and they are indifferent to it. A rare few applications that were uploaded nine years ago might actually still be okay but those are extremely rare exceptions. The last time I reported this nuget problem nothing happened on the issue until I tweeted about it. This time around, a well-known Microsoft developer (who shall remain nameless here) saw my Mastodon post about this topic when mirrored over to Bluesky and pushed for the case internally – but not even that helped. The nuget management thinks this is okay. If I were into puns I would probably call them chicken nuget for their unwillingness to fix this. Maybe just closing our eyes and pretending it doesn’t exist will just make it go away? Absolutely no one should use nuget.

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daniel.haxx.se 1 weeks ago

curl 8.19.0

Release presentation Welcome to the curlhacker stream at 10:00 CET (09:00 UTC) today March 11, 2026 for a live-streamed presentation of curl 8.19.0. The changes, the security fixes and some bugfixes. the 273rd release 8 changes 63 days (total: 10,712) 264 bugfixes (total: 13,640) 538 commits (total: 38,024) 0 new public libcurl function (total: 100) 0 new curl_easy_setopt() option (total: 308) 0 new curl command line option (total: 273) 77 contributors, 48 new (total: 3,619) 37 authors, 21 new (total: 1,451) 4 security fixes (total: 180) We stopped the bug-bounty but it has not stopped people from finding vulnerabilities in curl. The following upcoming changes might be worth noticing. See the deprecate documentation for details. We plan to ship the next curl release on April 29. See you then! CVE-2026-1965: bad reuse of HTTP Negotiate connection CVE-2026-3783: token leak with redirect and netrc CVE-2026-3784: wrong proxy connection reuse with credentials CVE-2026-3805: use after free in SMB connection reuse We stopped the bug-bounty. It’s worth repeating, even if it was no code change. The cmake build got a option Initial support for MQTTS was merged curl now supports fractions for –limit-rate and –max-filesize curl’s -J option now uses the redirect name as a backup we no longer support OpenSSL-QUIC on Windows, curl can now get built to use the native CA store by default the minimum Windows version curl supports is now Vista (up from XP) NTLM support becomes opt-in RTMP support is getting dropped SMB support becomes opt-in Support for c-ares versions before 1.16 goes away Support for CMake 3.17 and earlier gets dropped TLS-SRP support will be removed

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daniel.haxx.se 1 weeks ago

Dependency tracking is hard

curl and libcurl are written in C. Rather low level components present in many software systems. They are typically not part of any ecosystem at all. They’re just a tool and a library. In lots of places on the web when you mention an Open Source project, you will also get the option to mention in which ecosystem it belongs. npm, go, rust, python etc. There are easily at least a dozen well-known and large ecosystems. curl is not part of any of those. Recently there’s been a push for PURLs ( Package URLs ), for example when describing your specific package in a CVE. A package URL only works when the component is part of an ecosystem. curl is not. We can’t specify curl or libcurl using a PURL. SBOM generators and related scanners use package managers to generate lists of used components and their dependencies . This makes these tools quite frequently just miss and ignore libcurl. It’s not listed by the package managers. It’s just in there, ready to be used. Like magic. It is similarly hard for these tools to figure out that curl in turn also depends and uses other libraries. At build-time you select which – but as we in the curl project primarily just ships tarballs with source code we cannot tell anyone what dependencies their builds have. The additional libraries libcurl itself uses are all similarly outside of the standard ecosystems. Part of the explanation for this is also that libcurl and curl are often shipped bundled with the operating system many times, or sometimes perceived to be part of the OS. Most graphs, SBOM tools and dependency trackers therefore stop at the binding or system that uses curl or libcurl, but without including curl or libcurl. The layer above so to speak. This makes it hard to figure out exactly how many components and how much software is depending on libcurl. A perfect way to illustrate the problem is to check GitHub and see how many among its vast collection of many millions of repositories that depend on curl. After all, curl is installed in some thirty billion installations, so clearly it used a lot . (Most of them being libcurl of course.) It lists one dependency for curl. Repositories that depend on curl/curl: one. Screenshot taken on March 9, 2026 What makes this even more amusing is that it looks like this single dependent repository ( Pupibent/spire ) lists curl as a dependency by mistake.

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daniel.haxx.se 1 weeks ago

10K curl downloads per year

The Linux Foundation, the organization that we want to love but that so often makes that a hard bargain, has created something they call “Insights” where they gather lots of metrics on Open Source projects. I held back so I never blogged and taunted OpenSSF for their scorecard attempts that were always lame and misguided. This Insights thing looks like their next attempt to “grade” and “rate” Open Source. It is so flawed and full of questionable details that I decided there is no point in me listing them all in a blog post – it would just be too long and boring. Instead I will just focus on a single metric. The one that made me laugh out loud when I saw it. They claim curl was downloaded 10,467 times the last year. ( source ) Number of curl downloads the last 365 days according to Linux Foundation What does “a download” mean? They refer to statistics from ecosyste.ms , which is an awesome site and service, but it has absolutely no idea about curl downloads. How often is curl “downloaded”? curl release tarballs are downloaded from curl.se at a rate of roughly 250,000 / month. curl images are currently pulled from docker at a rate of around 400,000 – 700,000 / day. curl is pulled from quay.io at roughly the same rate. curl’s git repository is cloned roughly 32,000 times / day curl is installed from Linux and BSD distributions at an unknown rate. curl, in the form of libcurl, is bundled in countless applications, games, devices, cars, TVs, printers and services, and we cannot even guess how often it is downloaded as such an embedded component. curl is installed by default on every Windows and macOS system since many years back. But no, 10,467 they say.

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daniel.haxx.se 3 weeks ago

curl up 2026

The annual curl users and developers meeting, curl up, takes place May 23-24 2026 in Prague, Czechia. We are in fact returning to the same city and the exact same venue as in 2025. We liked it so much! This is a cozy and friendly event that normally attracts around 20-30 attendees. We gather in a room through a weekend and we talk curl. The agenda is usually setup with a number of talks through the two days, and each talk ends with a follow-up Q&A and discussion session. So no big conference thing, just a bunch of friends around a really large table. Over a weekend. Anyone is welcome to attend – for free – and everyone is encouraged to submit a talk proposal – anything that is curl and Internet transfer related goes. We make an effort to attract and lure the core curl developers and the most active contributors of recent years into the room. We do this by reimbursing their travel and hotel expenses. The agenda is a collaborative effort and we are going to work on putting it together from now all the way until the event, in order to make sure we make the best of the weekend and we get to talk to and listen to all the curl related topics we can think of! Help us improve the Agenda in the curl-up wiki: https://github.com/curl/curl-up/wiki/2026 Meeting up in the real world as opposed to doing video meetings helps us get to know each other better, allows us to socialize in ways we otherwise never can do and in the end it helps us work better together – which subsequently helps us write better code and produce better outcomes! It also helps us meet and welcome newcomers and casual contributors. Showing up at curl up is an awesome way to dive into the curl world wholeheartedly and in the deep end. Needless to say this event costs money to run. We pay our top people to come, we pay for the venue and pay for food. We would love to have your company mentioned as top sponsor of the event or perhaps a social dinner on the Saturday? Get in touch and let’s get it done! Everyone is welcome and encouraged to attend – at no cost. We only ask that you register in advance (the registration is not open yet). We always record all sessions on video and make them available after the fact. You can catch up on previous years’ curl up sessions on the curl website’s video section . We also live-stream all the sessions on curl up during both days. To be found on my twitch channel: curlhacker . Our events are friendly to everyone. We abide to the code of conduct and we never had anyone be even close to violating that,

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daniel.haxx.se 3 weeks ago

curl security moves again

tldr: curl goes back to Hackerone. When we announced the end of the curl bug-bounty at the end of January 2026, we simultaneously moved over and started accepting curl security reports on GitHub instead of its previous platform. This move turns out to have been a mistake and we are now undoing that part of the decision. The reward money is still gone, there is no bug-bounty , no money for vulnerability reports, but we return to accepting and handling curl vulnerability and security reports on Hackerone . Starting March 1st 2026, this is now (again) the official place to report security problems to the curl project. This zig-zagging is unfortunate but we do it with the best of intentions. In the curl security team we were naively thinking that since so many projects are already using this setup it should be good enough for us too since we don’t have any particular special requirements. We wrongly thought . Now I instead question how other Open Source projects can use this. It feels like an area and use case for Open Source projects that is under-focused: proper, secure and efficient vulnerability reporting without bug-bounty. To illustrate what we are looking for, I made a little list that should show that we’re not looking for overly crazy things. Here is a list of nits and missing features we fell over on GitHub that, had we figured them out ahead of time, possibly would have made us go about this a different way. This list might interest fellow maintainers having the same thoughts and ideas we had. I have provided this feedback to GitHub as well – to make sure they know . Sure, we could switch to handling them all over email but that also has its set of challenges. Including: Since we dropped the bounty, the inflow tsunami has dried out substantially . Perhaps partly because of our switch over to GitHub? Perhaps it just takes a while for all the sloptimists to figure out where to send the reports now and perhaps by going back to Hackerone we again open the gates for them? We just have to see what happens. We will keep iterating and tweaking the program, the settings and the hosting providers going forward to improve. To make sure we ship a robust and secure set of products and that the team doing so can do that If you suspect a security problem in curl or libcurl, report it here: https://hackerone.com/curl Gitlab, Codeberg and others are GitHub alternatives and competitors, but few of them offer this kind of security reporting feature. That makes them bad alternatives or replacements for us for this particular service. Incoming submissions are reports that identify security problems . The reporter needs an account on the system. Submissions start private; only accessible to the reporter and the curl security team All submissions must be disclosed and made public once dealt with. Both correct and incorrect ones. This is important. We are Open Source. Maximum transparency is key. There should be a way to discuss the problem amongst security team members, the reporter and per-report invited guests. It should be possible to post security-team-only messages that the reporter and invited guests cannot see For confirmed vulnerabilities, an advisory will be produced that the system could help facilitate If there’s a field for CVE, make it possible to provide our own. We are after all our own CNA. Closed and disclosed reports should be clearly marked as invalid/valid etc Reports should have a tagging system so that they can be marked as “AI slop” or other terms for statistical and metric reasons Abusive users should be possible to ban/block from this program Additional (customizable) requirements for the privilege of submitting reports is appreciated (rate limit, time since account creation, etc) GitHub sends the whole report over email/notification with no way to disable this. SMTP and email is known for being insecure and cannot assure end to end protection. This risks leaking secrets early to the entire email chain. We can’t disclose invalid reports (and make them clearly marked as such) Per-repository default collaborators on GitHub Security Advisories is annoying to manage, as we now have to manually add the security team for each advisory or have a rather quirky workflow scripting it. https://github.com/orgs/community/discussions/63041 We can’t edit the CVE number field! We are a CNA, we mint our own CVE records so this is frustrating. This adds confusion. We want to (optionally) get rid of the CVSS score + calculator in the form as we actively discourage using those in curl CVE records No CI jobs working in private forks is going to make us effectively not use such forks, but is not a big obstacle for us because of our vulnerability working process. https://github.com/orgs/community/discussions/35165 No “quote” in the discussions? That looks… like an omission. We want to use GitHub’s security advisories as the report to the project, not the final advisory (as we write that ourselves) which might get confusing, as even for the confirmed ones, the project advisories (hosted elsewhere) are the official ones, not the ones on GitHub No number of advisories count is displayed next to “security” up in the tabs, like for issues and Pull requests. This makes it hard to see progress/updates. When looking at an individual advisory, there is no direct button/link to go back to the list of current advisories In an advisory, you can only “report content”, there is no direct “block user” option like for issues There is no way to add private comments for the team-only, as when discussing abuse or details not intended for the reporter or other invited persons in the issue There is a lack of short (internal) identifier or name per issue, which makes it annoying and hard to refer to specific reports when discussing them in the security team. The existing identifiers are long and hard to differentiate from each other. You quite weirdly cannot get completion help for in comments to address people that were added into the advisory thanks to them being in a team you added to the issue? There are no labels, like for issues and pull requests, which makes it impossible for us to for example mark the AI slop ones or other things, for statistics, metrics and future research Hard to keep track of the state of each current issue when a number of them are managed in parallel. Even just to see how many cases are still currently open or in need of attention. Hard to publish and disclose the invalid ones, as they never cause an advisory to get written and we rather want the initial report and the full follow-up discussion published. Hard to adapt to or use a reputation system beyond just the boolean “these people are banned”. I suspect that we over time need to use more crowdsourced knowledge or reputation based on how the reporters have behaved previously or in relation to other projects.

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daniel.haxx.se 3 weeks ago

decomplexification continued

Last spring I wrote a blog post about our ongoing work in the background to gradually simplify the curl source code over time. This is a follow-up: a status update of what we have done since then and what comes next. In May 2025 I had just managed to get the worst function in curl down to complexity 100, and the average score of all curl production source code (179,000 lines of code) was at 20.8. We had 15 functions still scoring over 70. Almost ten months later we have reduced the most complex function in curl from 100 to 59. Meaning that we have simplified a vast number of functions. Done by splitting them up into smaller pieces and by refactoring logic. Reviewed by humans, verified by lots of test cases, checked by analyzers and fuzzers, The current 171,000 lines of code now has an average complexity of 15.9. The complexity score in this case is just the cold and raw metric reported by the pmccabe tool. I decided to use that as the absolute truth, even if of course a human could at times debate and argue about its claims. It makes it easier to just obey to the tool, and it is quite frankly doing a decent job at this so it’s not a problem. In almost all cases the main problem with complex functions is that they do a lot of things in a single function – too many – where the functionality performed could or should rather be split into several smaller sub functions. In almost every case it is also immediately obvious that when splitting a function into two, three or more sub functions with smaller and more specific scopes, the code gets easier to understand and each smaller function is subsequently easier to debug and improve. I don’t know how far we can take the simplification and what the ideal average complexity score of a the curl code base might be. At some point it becomes counter-effective and making functions even smaller then just makes it harder to follow code flows and absorbing the proper context into your head. To illustrate our simplification journey, I decided to render graphs with a date axle starting at 2022-01-01 and ending today. Slightly over four years, representing a little under 10,000 git commits. First, a look a the complexity of the worst scored function in curl production code over the last four years. Comparing with P90 and P99. The most complex function in curl over time Identifying the worst function might not say too much about the code in general, so another check is to see how the average complexity has changed. This is calculated like this: For all functions, add its function-score x function-length to a total complexity score, and in the end, divide that total complexity score on total number of lines used for all functions. Also do the same for a median score. Average and median complexity per source code line in curl, over time. When 2022 started, the average was about 46 and as can be seen, it has been dwindling ever since, with a few steep drops when we have merged dedicated improvement work. One way to complete the average and median lines to offer us a better picture of the state, is to investigate the complexity distribution through-out the source code. How big portion of the curl source code is how complex This reveals that the most complex quarter of the code in 2022 has since been simplified. Back then 25% of the code scored above 60, and now all of the code is below 60. It also shows that during 2025 we managed to clean up all the dark functions, meaning the end of 100+ complexity functions. Never to return, as the plan is at least. We don’t really know. We believe less complex code is generally good for security and code readability, but I it is probably still too early for us to be able to actually measure any particular positive outcome of this work (apart from fancy graphs). Also, there are many more ways to judge code than by this complexity score alone. Like having sensible APIs both internal and external and making sure that they are properly and correctly documented etc. The fact that they all interact together and they all keep changing, makes it really hard to isolate a single factor like complexity and say that changing this alone is what makes an impact. Additionally: maybe just the refactor itself and the attention to the functions when doing so either fix problems or introduce new problems, that is then not actually because of the change of complexity but just the mere result of eyes giving attention on that code and changing it right then. Maybe we just need to allow several more years to pass before any change from this can be measured? All functions get a complexity score by pmccabe Each function has a number of lines

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daniel.haxx.se 1 months ago

Open Source security in spite of AI

The title of my ending keynote at FOSDEM February 1, 2026. As the last talk of the conference, at 17:00 on the Sunday lots of people had already left, and presumably a lot of the remaining people were quite tired and ready to call it a day. Still, the 1500 seats in Janson got occupied and there was even a group of more people outside wanting to get in that had to be refused entry. Thanks to the awesome FOSDEM video team, the recording was made available this quickly after the presentation. You can also get the video off FOSDEM servers . The 59 slide PDF version .

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daniel.haxx.se 1 months ago

A third medal

In January 2025 I received the European Open Source Achievement Award . The physical manifestation of that prize was a trophy made of translucent acrylic (or something similar). The blog post I above has a short video where I show it off. In the year that passed since, we have established an organization for how do the awards going forward in the European Open Source Academy and we have arranged the creation of actual medals for the awardees. That was the medal we gave the award winners last week at the award ceremony where I handed Greg his prize. I was however not prepared for it, but as a direct consequence I was handed a medal this year , in recognition for the award a got last year , because now there is a medal. A retroactive medal if you wish. It felt almost like getting the award again. An honor. The box The backside Front The medal design The medal is made in a shiny metal, roughly 50mm in diameter. In the middle of it is a modern version (with details inspired by PCB looks) of the Yggdrasil tree from old Norse mythology – the “World Tree”. A source of life, a sacred meeting place for gods. In a circle around the tree are twelve stars , to visualize the EU and European connection. On the backside, the year and the name are engraved above an EU flag, and the same circle of twelve stars is used there as a margin too, like on the front side. The medal has a blue and white ribbon, to enable it to be draped over the head and hung from the neck. The box is sturdy thing in dark blue velvet-like covering with European Open Source Academy printed on it next to the academy’s logo. The same motif is also in the inside of the top part of the box. I do feel overwhelmed and I acknowledge that I have receive many medals by now. I still want to document them and show them in detail to you, dear reader. To show appreciation; not to boast.

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daniel.haxx.se 1 months ago

GregKH awarded the Prize for Excellence in Open Source 2026

I had the honor and pleasure to hand over this prize to its first real laureate during the award gala on Thursday evening in Brussels, Belgium. This annual award ceremony is one of the primary missions for the European Open Source Academy , of which I am the president since last year. As an academy, we hand out awards and recognition to multiple excellent individuals who help make Europe the home of excellent Open Source. Fellow esteemed academy members joined me at this joyful event to perform these delightful duties. As I stood on the stage, after a brief video about Greg was shown I introduced Greg as this year’s worthy laureate. I have included the said words below. Congratulations again Greg. We are lucky to have you. There are tens of millions of open source projects in the world, and there are millions of open source maintainers. Many more would count themselves as at least occasional open source developers. These are the quiet builders of Europe’s digital world. When we work on open source projects, we may spend most of our waking hours deep down in the weeds of code, build systems, discussing solutions, or tearing our hair out because we can’t figure out why something happens the way it does, as we would prefer it didn’t. Open source projects can work a little like worlds on their own. You live there, you work there, you debate with the other humans who similarly spend their time on that project. You may not notice, think, or even care much about other projects that similarly have a set of dedicated people involved. And that is fine. Working deep in the trenches this way makes you focus on your world and maybe remain unaware and oblivious to champions in other projects. The heroes who make things work in areas that need to work for our lives to operate as smoothly as they, quite frankly, usually do. Greg Kroah-Hartman, however, our laureate of the Prize for Excellence in Open Source 2026, is a person whose work does get noticed across projects. Our recognition of Greg honors his leading work on the Linux kernel and in the Linux community, particularly through his work on the stable branch of Linux. Greg serves as the stable kernel maintainer for Linux, a role of extraordinary importance to the entire computing world. While others push the boundaries of what Linux can do, Greg ensures that what already exists continues to work reliably. He issues weekly updates containing critical bug fixes and security patches, maintaining multiple long-term support versions simultaneously. This is work that directly protects billions of devices worldwide. It’s impossible to overstate the importance of the work Greg has done on Linux. In software, innovation grabs headlines, but stability saves lives and livelihoods. Every Android phone, every web server, every critical system running Linux depends on Greg’s meticulous work. He ensures that when hospitals, banks, governments, and individuals rely on Linux, it doesn’t fail them. His work represents the highest form of service: unglamorous, relentless, and essential. Without maintainers like Greg, the digital infrastructure of our world would crumble. He is, quite literally, one of the people keeping the digital infrastructure we all depend on running. As a fellow open source maintainer, Greg and I have worked together in the open source security context. Through my interactions with him and people who know him, I learned a few things: An American by origin, Greg now calls Europe his home, having lived in the Netherlands for many years. While on this side of the pond, he has taken on an important leadership role in safeguarding and advocating for the interests of the open source community. This is most evident through his work on the Cyber Resilience Act, through which he has educated and interacted with countless open source contributors and advocates whose work is affected by this legislation. We — if I may be so bold — the Open Source community in Europe — and yes, the whole world, in fact — appreciate your work and your excellence. Thank you, Greg. Please come on stage and collect your award. Greg is competent. a custodian and maintainer of many parts and subsystems of the Linux kernel tree and its development for decades. Greg has a voice. He doesn’t bow to pressure or take the easy way out. He has integrity. Greg is persistent. He has been around and done hard work for the community for decades. Greg is a leader. He shares knowledge, spreads the word, and talks to crowds. In a way that is heard and appreciated. He is a mentor.

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daniel.haxx.se 1 months ago

curl distro meeting 2026

We are doing another curl + distro online meeting this spring in what now has become an established annual tradition. A two-hour discussion, meeting, workshop for curl developers and curl distro maintainers. 2026 curl distro meeting details The objective for these meetings is simply to make curl better in distros. To make distros do better curl. To improve curl in all and every way we think we can, together. A part of this process is to get to see the names and faces of the people involved and to grease the machine to improve cross-distro collaboration on curl related topics. Anyone who feels this is a subject they care about is welcome to join. We aim for the widest possible definition of distro and we don’t attempt to define the term. The 2026 version of this meeting is planned to take place in the early evening European time, morning west coast US time. With the hope that it covers a large enough amount of curl interested people. The plan is to do this on March 26 , and all the details, planning and discussion items are kept on the dedicated wiki page for the event . Please add your own discussion topics that you want to know or talk about, and if you feel inclined, add yourself as an intended participant. Feel free to help make this invite reach the proper people. See you on March 26!

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daniel.haxx.se 1 months ago

Improving curl -J

We introduced curl’s option , also known as back in February 2010. A decent amount of years ago. The option is used in combination with ( ) when downloading data from a HTTP(S) server and instructs curl to use the filename in the incoming header when saving the content, instead of the filename of the URL passed on the command line (if provided). That header would later be explained further in RFC 6266 . The idea is that for some URLs the server can provide a more suitable target filename than what the URL contains from the beginning. Like when you do a command similar to: Without -J, the content would be save in the target output filename called ‘download’ – since curl strips off the query part. With -J, curl parses the server’s response header that contains a better filename; in the example below fun.jpg . The above approach mentioned works pretty well, but has several limitations. One of them being that the obvious that if the site instead of providing a Content-Disposition header perhaps only redirects the client to a new URL to the download from, curl does not pick up the new name but instead keeps using the one from the originally provided URL. This is not what most users want and not what they expect. As a consequence, we have had this potential improvement mentioned in the TODO file for many years. Until today . We have now merged a change that makes curl with -J pick up the filename from Location: headers and it uses that filename if no Content-Disposition. This means that if you now rerun a similar command line as mentioned above, but this one is allowed to follow redirects: And that site redirects curl to the actual download URL for the tarball you want to download: … curl now saves the contents of that transfer in a local file called . If there is both a redirect and a Content-Disposition header, the latter takes precedence. Since this gets the filename from the server’s response, you give up control of the name to someone else. This can of course potentially mess things up for you. curl ignores all provided directory names and only uses the filename part. If you want to save the download in a dedicated directory other than the current one, use –output-dir . As an additional precaution, using -J implies that curl avoids to clobber, overwrite, any existing files already present using the same filename unless you also use –clobber . Since the selected final name used for storing the data is selected based on contents of a header passed from the server, using this option in a scripting scenario introduces the challenge: what filename did curl actually use? A user can easily extract this information with curl’s -w option . Like this: This command line outputs the used filename to stdout. Tweak the command line further to instead direct that name to stderr or to a specific file etc. Whatever you think works. The content-disposition RFC mentioned above details a way to provide a filename encoded as UTF-8 using something like the below, which includes a U+20AC Euro sign: curl still does not support this filename* style of providing names. This limitation remains because curl cannot currently convert that provided name into a local filename using the provided characters – with certainty. Room for future improvement! This -J improvement ships in curl 8.19.0, coming in March 2026.

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daniel.haxx.se 1 months ago

The end of the curl bug-bounty

tldr: an attempt to reduce the terror reporting . There is no longer a curl bug-bounty program. It officially stops on January 31, 2026. After having had a few half-baked previous takes, in April 2019 we kicked off the first real curl bug-bounty with the help of Hackerone, and while it stumbled a bit at first it has been quite successful I think. We attracted skilled researchers who reported plenty of actual vulnerabilities for which we paid fine monetary rewards. We have certainly made curl better as a direct result of this: 87 confirmed vulnerabilities and over 100,000 USD paid as rewards to researchers. I’m quite happy and proud of this accomplishment. I would like to especially highlight the awesome Internet Bug Bounty project, which has paid the bounties for us for many years. We could not have done this without them. Also of course Hackerone, who has graciously hosted us and been our partner through these years. Looking back, I think we can say that the downfall of the bug-bounty program started slowly in the second half of 2024 but accelerated badly in 2025. We saw an explosion in AI slop reports combined with a lower quality even in the reports that were not obvious slop – presumably because they too were actually misled by AI but with that fact just hidden better. Maybe the first five years made it possible for researchers to find and report the low hanging fruit. Previous years we have had a rate of somewhere north of 15% of the submissions ending up confirmed vulnerabilities. Starting 2025, the confirmed-rate plummeted to below 5%. Not even one in twenty was real . The never-ending slop submissions take a serious mental toll to manage and sometimes also a long time to debunk. Time and energy that is completely wasted while also hampering our will to live. I have also started to get the feeling that a lot of the security reporters submit reports with a bad faith attitude. These “helpers” try too hard to twist whatever they find into something horribly bad and a critical vulnerability, but they rarely actively contribute to actually improve curl. They can go to extreme efforts to argue and insist on their specific current finding, but not to write a fix or work with the team on improving curl long-term etc. I don’t think we need more of that. There are these three bad trends combined that makes us take this step: the mind-numbing AI slop, humans doing worse than ever and the apparent will to poke holes rather than to help. In an attempt to do something about the sorry state of curl security reports, this is what we do: We believe that we can maintain and continue to evolve curl security in spite of this change. Maybe even improve thanks to this, as hopefully this step helps prevent more people pouring sand into the machine. Ideally we reduce the amount of wasted time and effort. I believe the best and our most valued security reporters still will tell us when they find security vulnerabilities. If you suspect a security problem in curl going forward, we advise you to head over to GitHub and submit them there. Alternatively, you send an email with the full report to . In both cases, the report is received and handled privately by the curl security team. But with no monetary reward offered . Hackerone was good to us and they have graciously allowed us to run our program on their platform for free for many years. We thank them for that service. As we now drop the rewards, we feel it makes a clear cut and displays a clearer message to everyone involved by also moving away from Hackerone as a platform for vulnerability reporting. It makes the change more visible. It is probably going to be harder for us to publicly disclose every incoming security report in the same way we have done it on Hackerone for the last year. We need to work out something to make sure that we can keep doing it at least imperfectly, because I believe in the goodness of such transparency. Let me emphasize that this change does not impact our presence and mode of operation with the curl repository and its hosting on GitHub . We hear about projects having problems with low-quality AI slop submissions on GitHub as well, in the form of issues and pull-requests, but for curl we have not (yet) seen this – and frankly I don’t think switching to a GitHub alternative saves us from that. Compared to others, we seem to be affected by the sloppy security reports to a higher degree than the average Open Source project. With the help of Hackerone, we got numbers of how the curl bug-bounty has compared with other programs over the last year. It turns out curl’s program has seen more volume and noise than other public open source bug bounty programs in the same cohort. Over the past four quarters, curl’s inbound report volume has risen sharply, while other bounty-paying open source programs in the cohort, such as Ruby, Node, and Rails, have not seen a meaningful increase and have remained mostly flat or declined slightly. In the chart, the pink line represents curl’s report volume, and the gray line reflects the broader cohort. Inbound Report Volume on Hackerone: curl compared to OSS peers We suspect the idea of getting money for it is a big part of the explanation. It brings in real reports, but makes it too easy to be annoying with little to no penalty to the user. The reputation system and available program settings were not sufficient for us to prevent sand from getting into the machine. The exact reason why we suffer more of this abuse than others remains a subject for further speculation and research. There is a non-zero risk that our guesses are wrong and that the volume and security report frequency will keep up even after these changes go into effect. If that happens, we will deal with it then and take further appropriate steps. I prefer not to overdo things or overplan already now for something that ideally does not happen. People keep suggesting that one way to deal with the report tsunami is to charge security researchers a small amount of money for the privilege of submitting a vulnerability report to us. A curl reporters security club with an entrance fee. I think that is a less good solution than just dropping the bounty. Some of the reasons include: Maybe we need to do this later anyway, but we stay away from it for now. We have seen other projects and repositories see similar AI-induced problems for pull requests, but this has not been a problem for the curl project. I believe that for PRs we have much better means to sort out the weed with automatic means, since we have tools, tests and scanners to verify such contributions. We don’t need to waste any human time on pull requests until the quality is good enough to get green check-marks from 200 CI jobs. I will do a talk at FOSDEM 2026 titled Open Source Security in spite of AI that of course will touch on this subject. We never say never. This is now and we might have reasons to reconsider and make a different decision in the future. If we do, we will let you know. These changes are applied now with the hope that they will have a positive effect for the project and its maintainers. If that turns out to not be the outcome, we will of course continue and apply further changes later. Since I created the pull request for updating the bug-bounty information for curl on January 14, almost two weeks before we merged it, various media picked up the news and published articles. Long before I posted this blog post. Also discussed (indirectly) on Hacker News . We no longer offer any monetary rewards for security reports – no matter which severity. In an attempt to remove the incentives for submitting made up lies. We stop using Hackerone as the recommended channel to report security problems. To make the change immediately obvious and because without a bug-bounty program we don’t need it. We refer everyone to submit suspected curl security problems on GitHub using their Private vulnerability reporting feature. We continue to immediately ban and publicly ridicule everyone who submits AI slop to the project. Charging people money in an International context is complicated and a maintenance burden. Dealing with charge-backs, returns and other complaints and friction add work. It would limit who could or would submit issues. Even some who actually find legitimate issues. The Register: Curl shutters bug bounty program to remove incentive for submitting AI slop Elektroniktidningen: cURL removes bug bounties Heise online: curl: Projekt beendet Bug-Bounty-Programm Neowin: Beloved tool, cURL is shutting down its bug bounty over AI slop reports Golem: Curl-Entwickler dreht dem “KI-Schrott” den Geldhahn zu Linux Easy: cURL chiude il programma bug bounty: troppi report generati dall’AI Bleeping Computer: Curl ending bug bounty program after flood of AI slop reports The New Stack: Drowning in AI slop, cURL ends bug bounties Ars Technica: Overrun with AI slop, cURL scraps bug bounties to ensure “intact mental health” PressMind Labs: cURL konczy program bug bounty – czy to koniec jakosci zgloszen? Socket: curl Shuts Down Bug Bounty Program After Flood of AI Slop Reports

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daniel.haxx.se 2 months ago

libcurl memory use some years later

One of the trickier things in software is gradual degradation. Development that happens in the wrong direction slowly over time which never triggers any alarms or upset users. Then one day you suddenly take a closer look at it and you realize that this area that used to be so fine several years ago no longer is. Memory use is one of those things. It is easy to gradually add more and larger allocations over time as we add features and make new cool architectural designs. curl and libcurl literally run in billions of installations and it is important for us that we keep memory use and allocation count to a minimum. It needs to run on small machines and it needs to be able to scale to large number of parallel connections without draining available resources. So yes, even in 2026 it is important to keep allocations small and as few as possible. In July 2025 we added a test case to curl’s test suite (3214) that simply checks the sizes of fifteen important structs. Each struct has a fixed upper limit which they may not surpass without causing the test to fail. Of course we can adjust the limits when we need to, as it might be entirely okay to grow them when the features and functionalities motivate that, but this check makes sure that we do not mistakenly grow the sizes simply because of a mistake or bad planning. It’s of course a question of a balance. How much memory is a feature and added performance worth? Every libcurl user probably has their own answers to that but I decided to take a look at how we do today, and compare with data I blogged five years ago . The point in time I decided to compare with here, curl 7.75.0, is fun to use because it was a point in time where I had given the size use in curl some focused effort and minimization work. libcurl memory use was then made smaller and more optimized than it had been for almost a decade before that. The struct sizes always vary depending on which features that are enabled, but in my tests here they are “maximized”, with as many features and backends enabled as possible. Let’s take a look at three important structs. The multi handle, the easy handle and the connectdata struct. Now compared to then, five years ago. As seen in the table, two of the structs have grown and one has shrunken. Let’s see what impact that might have. If we assume a libcurl-using application doing 10 parallel transfers that have 20 concurrent connections open, libcurl five ago needed: 1472 x 20 + 5272 x 10 + 416 = 82,576 bytes for that While libcurl in current git needs: 912 x 20 + 5352 x 10 + 816 = 72,576 bytes. Incidentally that is exactly 10,000 bytes less, five years and many new features later. This said, part of the reason the structs chance is that we move data between them and to other structs. The few mentioned here are not the whole picture. Using a bleeding edge curl build, this command line on my 64 bit Linux Debian host does 107 allocations, that needs at its maximum 133,856 bytes. Compared to five years ago, where it needed 131,680 bytes done in a mere 96 allocations. curl now needs 1.6% more memory for this, done with 11% more allocation calls. I believe the current amounts are still okay consider we have refactored, developed and evolved the library significantly over the same period. As a comparison, downloading the same file twenty times in parallel over HTTP/1 using the same curl build needs 2,222 allocations but only a total of 308,613 bytes allocated at peak. Twenty times the number of allocations but only three times the maximum size, compared to the single file download. Caveat: this measures clear text HTTP downloads. Almost everything transferred these days is using TLS and if you add TLS to this transfer, curl itself does only a few additional allocations but more importantly the TLS library involved allocates much more memory and do many more allocations. I just consider those allocations to be someone else’s optimization work. I generated a few graphs that illustrate memory use changes in curl over time based on what I described above. The “easy handle” is the handle an application creates and that is associated which each individual transfer done with libcurl. curl easy handle size changes over time The “multi handle” is a handle that holds one or more easy handles. An application has at least one of these and adds many easy handles to it, or the easy handles has one of its own internally. curl multi handle size changes over time The “connectdata” is an internal struct for each existing connection libcurl knows about. A normal application that makes multiple transfers, either serially or in parallel tends to make the easy handle hold at least a few of these since libcurl uses a connection pool by default to use for subsequent transfers. curl connectdata struct size over time Here is data from the internal tracking of memory allocations done when the curl tool is invoked to download a 512 megabyte file from a locally hosted HTTP server. (Generally speaking though, downloading a larger size does not use more memory.) curl downloading a 512MB file needs this much memory and allocations Conclusion I think we are doing alright and none of these struct sizes or memory use have gone bad. We offer more features and better performance than ever, but keep memory spend at a minimum.

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daniel.haxx.se 2 months ago

Now with MQTTS

Back in 2020 we added MQTT support to curl. When curl 8.19.0 ships in the beginning of March 2026, we have also added MQTTS; meaning MQTT done securely over TLS. This bumps the number of supported transfer protocols to 29 not too long after the project turned 29 years old. The 29 transfer protocols (or schemes) that curl supports in January 2026 libcurl backends as of now What’s MQTT? Wikipedia describes it as a lightweight, publish–subscribe, machine-to-machine network protocol for message queue/message queuing service. It is designed for connections with remote locations that have devices with resource constraints or limited network bandwidth, such as in the Internet of things (IoT). It must run over a transport protocol that provides ordered, lossless, bi-directional connections—typically, TCP/IP. If things go as planned, the number of supported protocols will decrease soon as we have RTMP scheduled for removal later in the spring of 2026.

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daniel.haxx.se 2 months ago

My first 20,000 curl commits

Some of you may of course think what, only 20,000 commits after almost thirty years in the project, what kind of slacker is that guy? But yes, today I merged my 20,000th commit into the curl repository – out of a total of 37,604 commits (53%). Not that anyone is counting. 20,000 – Today, January 17, 2026 19,000 – March 2025 18,000 – February 2024 17,000 – December 2022 16,000 – November 2021 15,000 – September 2020 The first kept curl git commit is dated December 29, 1999. That is the date of our source code import into SourceForge as I quite annoyingly decided to not keep the prior history. The three years of development and the commits that happened before that import date are therefore not included in this count. These 20,000 commits have been done on 5,589 separate days, meaning 59% of all days since December 1999. It also means I have done an average of 2.1 commits per day since then. The curl commits done before 2010 were not actually made with git, but with CVS. The curl source repository was converted to git when we switched hosting over to GitHub. As of today, 1,431 separate individuals have authored commits merged into the curl source repository. 16 of us have made more than 100 commits. Five authors have written more than 1,000 commits. 941 of the authors only wrote a single commit (so far)! The second-most curl committer by number of commits (Yang Tse) has almost 2,600 commits but he stopped being active already back in 2013. The top-20 all time curl commit authors as of now: My share of the total amount of commits has been shrinking gradually since a long time and that is a good thing. It means we have awesome contributors and maintainers helping out. Not too far into the future I expect my share to go below 50%. the number of commits done by the top-20 commit authors in curl over time Number of commit authors in curl over time Number of unique authors per month over time Daniel’s share of authored commits over time Future These are my first 20,000 commits. I have no plans to go anywhere. I have averaged at about 800 commits per year in the curl source code repository for the last 25 years. That would imply reaching 30,000 would take another 12.5 years, so about by mid 2038 or so. If I manage to keep up that speed. Feels distant. This was my commit 20,000. Daniel Stenberg (20000 commits) Yang Tse (2587 commits) Viktor Szakats (2496 commits) Steve Holme (1916 commits) Dan Fandrich (1435 commits) Stefan Eissing (941 commits) Jay Satiro (773 commits) Guenter Knauf (662 commits) Gisle Vanem (498 commits) Marc Hoersken (461 commits) Marcel Raad (405 commits) Patrick Monnerat (362 commits) Kamil Dudka (255 commits) Daniel Gustafsson (217 commits) renovate[bot] (183 commits) Tatsuhiro Tsujikawa (150 commits) Michael Kaufmann (84 commits) Alessandro Ghedini (83 commits) Fabian Keil (77 commits) Nick Zitzmann (70 commits)

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daniel.haxx.se 2 months ago

More HTTP/3 focus, one backend less

In the curl project we have a long tradition of offering multiple optional backends for specific protocols. In this spirit we have added experimental support for a number of different HTTP/3 + QUIC backends over time. A while ago we dropped one of those experiments, the msh3 backend. Today we cleanup even more and remove support for yet another backend: the OpenSSL-QUIC stack and we are now down to only supporting two different HTTP/3 alternatives: the nghttp2 + nghttp3 combo or quiche. And out of those two, the quiche backend is still considered experimental. The first release shipping with this change will be curl 8.19.0. This is the QUIC stack implemented and provided by OpenSSL. To make matters a little complicated, this is a separate thing from the QUIC API that OpenSSL also offers. The first one is a full QUIC implementation, the second one is an API that is powerful enough to allow a separate QUIC implementation use OpenSSL for its cryptographic and TLS needs. 2019 – BoringSSL introduced an API for QUIC. QUIC implementations picked it up and it worked. A pull request was made for OpenSSL to allow them to provide the same API so that QUIC stacks all over could use OpenSSL. 2021 – OpenSSL eventually denied merging the pull-request and announced they would instead implement their own QUIC stack – that nobody had asked for. 2023 – OpenSSL 3.2 shipped with support for their own QUIC stack. It was broken in many ways. 2025: OpenSSL version 3.4.1 was released and now the QUIC stack worked decently . In OpenSSL 3.5.0 they announced a QUIC API that now finally allowed independent QUIC stacks to use OpenSSL. Skilled contributors added support for OpenSSL-QUIC to curl primarily to allow people using OpenSSL to still be able to use HTTP/3. OpenSSL’s own QUIC implementation only reached experimental state in curl meaning that we explicitly and strongly discourage users from using it in production and reserve ourselves the right to change functionality and more between versions. There are three reasons why it did not graduate from experimental and they are also the reasons why we think we are better off without offering support for it: This makes the curl backend situation simpler in the HTTP/3 and QUIC department as the image below tries to show. HTTP/3 backends in curl in January 2026 The API is lacking. We have communicated with the OpenSSL-QUIC team since even before the API first shipped and it still does not offer the knobs and controls we would like to make it a competitive QUIC alternative. We don’t feel they care much. The performance is bad. And by bad I mean really bad. The leading QUIC implementation alternative ngtcp2 transfers data much faster in all benchmarks and comparisons. Sometimes up to a factor three difference. The memory use is abysmal. The amount of more memory required to do transfers with OpenSSL-QUIC compared to ngtcp2 can reach a factor twenty.

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daniel.haxx.se 2 months ago

curl 8.18.0

Download curl from curl.se ! the 272nd release 5 changes 63 days (total: 10,155) 391 bugfixes (total: 13,376) 758 commits (total: 37,486) 0 new public libcurl function (total: 100) 0 new curl_easy_setopt() option (total: 308) 0 new curl command line option (total: 273) 69 contributors, 36 new (total: 3,571) 37 authors, 14 new (total: 1,430) 6 security fixes (total: 176) This time there is no less than six separate vulnerabilities announced. There are a few this time, mostly around dropping support for various dependencies: See the release presentation video for a walk-through of some of the most important/interesting fixes done for this release, or go check out the full list in the changelog . CVE-2025-13034 : skipping pinning check for HTTP/3 with GnuTLS CVE-2025-14017 : broken TLS options for threaded LDAPS CVE-2025-14524 : bearer token leak on cross-protocol redirect CVE-2025-14819 : OpenSSL partial chain store policy bypass CVE-2025-15079 : libssh global knownhost override CVE-2025-15224 : libssh key passphrase bypass without agent set drop support for VS2008 (Windows) drop Windows CE / CeGCC support drop support for GnuTLS < 3.6.5 gnutls: implement CURLOPT_CAINFO_BLOB openssl: bump minimum OpenSSL version to 3.0.0

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