All posts by Daniel Stenberg

cURL and libcurl

Approaching zero bugs?

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In this era of powerful tools to find software bugs, we now see tools find a lot of problems at a high speed. This causes problems for developers, as dealing with the growing list of issues is hard. It may take a longer time to address the problems than to find them – not to mention to put them into releases and then it takes yet another extended time until users out in the wild actually get that updated version into their hands.

In order to find many bugs fast, they have to already exist in source code. These new tools don’t add or create the problems. They just find them, filter them out and bring them to the surface for exposure. A better filter in the pool filters out more rubbish.

The more bugs we fix, the fewer bugs remain in the code. Assuming the developers manage to fix problems at a decent enough pace.

For every bugfix we merge, there is a risk that the change itself introduces one more more new separate problems. We also tend to keep adding features and changing behavior as we want to improve our products, and when doing so we occasionally slip up and introduce new problems as well.

Source code analyzing tools is a concept as old as source code itself. There has always existed tools that have tried to identify coding mistakes. Now they just recently got better so they can find more mistakes.

These new tools, similar to the old ones, don’t find all the problems. Even these new modern tools sometimes suggest fixes to the problems they find that are incomplete and in fact sometimes downright buggy.

Undoubtedly code analyzer tooling will improve further. The tools of tomorrow will find even more bugs, some of them were not found when the current generation of tools scanned the code yesterday.

Of course, we now also introduce these tools in CI and general development pipelines, which should make us land better code with fewer mistakes going forward. Ideally.

If we assume that we fix bugs faster than we introduce new ones and we assume that the AI tools can improve further, the question is then more how much more they can improve and for how long that improvement can go on. Will the tools find 10% more bugs? 100%? 1000%? Is the tool improving going to gradually continue for the next two, ten or fifty years? Can they actually find all bugs?

Can we reach the utopia where we have no bugs left in a given software project and when we do merge a new one, it gets detected and fixed almost instantly?

Are we close?

If we assume that there is at least a theoretical chance to reach that point, how would we know when we reach it? Or even just if we are getting closer?

I propose that one way to measure if we are getting closer to zero bugs is to check the age of reported and fixed bugs. If the tools are this good, we should soon only be fixing bugs we introduced very recently.

In the curl project we don’t keep track of the age of regular bugs, but we do for vulnerabilities. The worst kind of bugs. If the tools can find almost all problems, they should soon only be finding very recently added vulnerabilities too. The age of new finds should plummet and go towards zero.

If the age of newly reported vulnerabilities are getting younger, it should make the average and median age of the total collection go down over time.

Average age of vulnerabilities

The average and median time vulnerabilities had existed in the curl source code by the time they were found and reported to the project.

Accumulated vulnerability age when reported

Bugfixes

When the tools have found most problems there should be less bugs left to fix. The bugfix rate should go down rapidly – independently of how you count them or how liberal we are in counting exactly what is a bugfix.

Bugfixes

Given the data from the curl project, there does not seem to be fewer bugfixes done – yet. Maybe the bugfix speed goes up before it goes down?

We are not close

Given the look of these graphs I don’t think we are close to zero bugs yet. These two curves do not seem to even start to fall yet.

Yes, these graphs are based on data from a single project, which makes it super weak to draw statistical conclusions from, but this is all I have to work with.

So when?

I think that’s mostly an indication of what you believe the tooling can do and how good they can eventually end up becoming.

I don’t know. I will keep fixing bugs.

cURL and libcurl

Inspired

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The picture was taken by mr Nasser and shared on social media

In appendix A of the book Root cause: Stories and lessons from two decades of Backend Engineering Bugs, author Hussein Nasser has these wonderful words to say about me:

Daniel Stenberg is a Swedish engineer and the creator of curl (cURL), one of the most widely used tools and libraries for fetching content over various protocols. I’ve always admired Daniel’s work, reading his blogs and watching his talks on YouTube. He is one of the engineers who inspired me to start my own YouTube channel and teach backend engineering.

It warms my heart to read this. Words like this give me energy and motivation. My work has meaning.

cURL and libcurl

curl 8.20.0

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You always find the new curl releases on the curl site!

Release presentation

Numbers

the 274th release
8 changes
49 days (total: 10,761)
282 bugfixes (total: 13,922)
521 commits (total: 38,545)
0 new public libcurl function (total: 100)
0 new curl_easy_setopt() option (total: 308)
0 new curl command line option (total: 273)
73 contributors, 45 new (total: 3,664)
28 authors, 12 new (total: 1,463)
8 security fixes (total: 188)

Security

As mentioned elsewhere, the security reporting volume has been intense lately. We publish eight new curl vulnerabilities this time.

Changes

  • now uses a thread pool and queue for resolving
  • NTLM is disabled by default
  • dropped support for CMake 3.17 and older
  • dropped support for < c-ares 1.16.0
  • SMB is disabled by default
  • added CURLMNWC_CLEAR_ALL for all network changes
  • dropped RTMP support

Bugfixes

The official count says over 260 bugfixes were merged in this 49 day cycle. See the changelog for all the details.

Pending Removals

Planned upcoming removals include:

  • local crypto implementations
  • NTLM
  • SMB
  • TLS-SRP support

If you are concerned about any of these, speak up on the curl-library ASAP.

Next release

Unless we messed up this one and need to do a patch release, the pending next release is scheduled to happen on June 24.

cURL and libcurl

High-Quality Chaos

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As I have been preparing slides for my coming talk at foss-north on April 28, 2026 I figured I could take the opportunity and share a glimpse of the current reality here on my blog. The high quality chaos era, as I call it.

No more AI slop

I complained and I complained about the high frequency junk submissions to the curl bug-bounty that grew really intense during 2025 and early 2026. To the degree that we shut it down completely on February 1st this year. At the time we speculated if that would be sufficient or if the flood would go on.

Now we know.

Higher volume, higher quality

In March 2026, the curl project went back to Hackerone again once we had figured out that GitHub was not good enough.

From that day, the nature of the security report submissions have changed.

The slop situation is not a problem anymore.

AI slop rate

The report frequency is higher than ever. Recently it’s been about double the rate we had through 2025, which already was more than double from previous years.

Number of hours between security reports

The quality is higher. The rate of confirmed vulnerabilities is back to and even surpassing the 2024 pre-AI level, meaning somewhere in the 15-16% range.

Confirmed vulnerability rate

In addition to that, the share of reports that identify a bug, meaning that they aren’t vulnerabilities but still some kind of problem, is significantly higher than before.

Share of reports that were bugs, not vulnerabilities

Everything is AI now

Almost every security report now uses AI to various degrees. You can tell by the way they are worded, how the report is phrased and also by the fact that they now easily get very detailed duplicates in ways that can’t be done had they been written by humans.

The difference now compared to before however, is that they are mostly very high quality.

The reporters rarely mention exactly which AI tool or model they used (and really, we don’t care), but the evidence is strong that they used such help.

We are not unique

I did a quick unscientific poll on Mastodon to see if other Open Source projects see the same trends and man, do they! Friends from the following projects confirmed that they too see this trend. Of course the exact numbers and volumes vary, but it shows its not unique to any specific project.

Apache httpd, BIND, curl, Django, Elasticsearch Python client, Firefox, git, glibc, GnuTLS, GStreamer, Haproxy, Immich, libssh, libtiff, Linux kernel, OpenLDAP, PowerDNS, python, Prometheus, Ruby, Sequoia PGP, strongSwan, Temporal, Unbound, urllib3, Vikunja, Wireshark, wolfSSL, …

I bet this list of projects is just a random selection that just happened to see my question. You will find many more experiencing and confirming this reality view.

An explosion

When we ship curl 8.20.0 in the middle of next week – end of April 2026, we expect to announce at least six new vulnerabilities. Assuming that the trend keeps up for at least the rest of the year, and I think that is a fair assumption, we are looking at an estimated explosion and a record amount of CVEs to be published by the curl project this year.

We might publish closer to 50 curl vulnerabilities in 2026.

Number of published vulnerabilities

Given this universal trend, I cannot see how this pattern can not also be spotted and expected to happen in many other projects as well.

Where does it end?

The tools are still improving. We keep adding flaws when we do bugfixes and add new features.

Someone has suggested it might work as with fuzzing, that we will see a plateau within a few years. I suppose we just have to see how it goes.

This avalanche is going to make maintainer overload even worse. Some projects will have a hard time to handle this kind of backlog expansion without any added maintainers to help.

It is probably a good time for the bad guys who can easily find this many problems themselves by just using the same tools, before all the projects get time, manpower and energy to fix them.

Then everyone needs to update to the newly released fixed versions of all packages, which we know is likely to take an even longer time.

We are up for a bumpy ride.

cURL and libcurl

Don’t trust, verify

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Software and digital security should rely on verification, rather than trust. I want to strongly encourage more users and consumers of software to verify curl. And ideally require that you could do at least this level of verification of other software components in your dependency chains.

Attacks are omnipresent

With every source code commit and every release of software, there are risks. Also entirely independent of those.

Some of the things a widely used project can become the victim of, include…

  • Jia Tan is a skilled and friendly member of the project team but is deliberately merging malicious content disguised as something else.
  • An established committer might have been breached unknowingly and now their commits or releases contain tainted bits.
  • A rando convinced us to merge what looks like a bugfix but is a small step in a long chain of tiny pieces building up a planted vulnerability or even backdoor
  • Someone blackmails or extorts an existing curl team member into performing changes not otherwise accepted in the project
  • A change by an established and well-meaning project member that adds a feature or fixes a bug mistakenly creates a security vulnerability.
  • The website on which tarballs are normally distributed gets hacked and now evil alternative versions of the latest release are provided, spreading malware.
  • Credentials of a known curl project member is breached and misinformation gets distributed appearing to be from a known and trusted source. Via email, social media or websites. Could even be this blog!
  • Something in this list is backed up by an online deep-fake video where a known project member seemingly repeats something incorrect to aid a malicious actor.
  • A tool used in CI, hosted by a cloud provider, is hacked and runs something malicious
  • While the primary curl git repository has a downtime, someone online (impersonating a curl team member?) offers a temporary “curl mirror” that contains tainted code.

In the event any of these would happen, they could of course also happen in combinations and in a rapid sequence.

You can verify

curl, mostly in the shape of libcurl, runs in tens of billions of devices. Clearly one of the most widely used software components in the world.

People ask me how I sleep at night given the vast amount of nasty things that could occur virtually at any point.

There is only one way to combat this kind of insomnia: do everything possible and do it openly and transparently. Make it a little better this week than it was last week. Do software engineering right. Provide means for everyone to verify what we do and what we ship. Iterate, iterate, iterate.

If even just a few users verify that they got a curl release signed by the curl release manager and they verify that the release contents is untainted and only contains bits that originate from the git repository, then we are in a pretty good state. We need enough independent outside users to do this, so that one of them can blow the whistle if anything at any point would look wrong.

I can’t tell you who these users are, or in fact if they actually exist, as they are and must be completely independent from me and from the curl project. We do however provide all the means and we make it easy for such users to do this verification.

We must verify

The few outsiders who verify that nothing was tampered with in the releases can only validate that the releases are made from what exists in git. It is our own job to make sure that what exists in git is the real thing. The secure and safe curl.

We must do a lot to make sure that whatever we land in git is okay. Here’s a list of activities we do.

  1. we have a consistent code style (invalid style causes errors). This reduces the risk for mistakes and makes it easier to debug existing code.
  2. we ban and avoid a number of “sensitive” and “hard-to-use” C functions (use of such functions causes errors)
  3. we have a ceiling for complexity in functions to keep them easy to follow, read and understand (failing to do so causes errors)
  4. we review all pull requests before merging, both with humans and with bots. We link back commits to their origin pull requests in commit messages.
  5. we ban use of “binary blobs” in git to not provide means for malicious actors to bundle encrypted payloads (trying to include a blob causes errors)
  6. we actively avoid base64 encoded chunks as they too could function as ways to obfuscate malicious contents
  7. we ban most uses of Unicode in code and documentation to avoid easily mixed up characters that look like other characters. (adding Unicode characters causes errors)
  8. we document everything to make it clear how things are supposed to work. No surprises. Lots of documentation is tested and verified in addition to spellchecks and consistent wording.
  9. we have thousands of tests and we add test cases for (ideally) every functionality. Finding “white spots” and adding coverage is a top priority. curl runs on countless operating systems, CPU architectures and you can build curl in billions of different configuration setups: not every combination is practically possible to test
  10. we build curl and run tests in over two hundred CI jobs that are run for every commit and every PR. We do not merge commits that have unexplained test failures.
  11. we build curl in CI with the most picky compiler options enabled and we never allow compiler warnings to linger. We always use -Werror that converts warnings to errors and fail the builds.
  12. we run all tests using valgrind and several combinations of sanitizers to find and reduce the risk for memory problems, undefined behavior and similar
  13. we run all tests as “torture tests”, where each test case is rerun to have every invoked fallible function call fail once each, to make sure curl never leaks memory or crashes due to this.
  14. we run fuzzing on curl: non-stop as part of Google’s OSS-Fuzz project, but also briefly as part of the CI setup for every commit and PR
  15. we make sure that the CI jobs we have for curl never “write back” to curl. They access the source repository read-only and even if they would be breached, they cannot infect or taint source code.
  16. we run zizmor and other code analyzer tools on the CI job config scripts to reduce the risk of us running or using insecure CI jobs.
  17. we are committed to always fix reported vulnerabilities in the following release. Security problems never linger around once they have been reported.
  18. we document everything and every detail about all curl vulnerabilities ever reported
  19. our commitment to never breaking ABI or API allows all users to easily upgrade to new releases. This enables users to run recent security-fixed versions instead of legacy insecure versions.
  20. our code has been audited several times by external security experts, and the few issues that have been detected in those were immediately addressed
  21. Two-factor authentication on GitHub is mandatory for all committers

All this done in the open with full transparency and full accountability. Anyone can follow along and verify that we follow this.

Require this for all your dependencies.

Not paranoia

We plan for the event when someone actually wants and tries to hurt us and our users really bad. Or when that happens by mistake. A successful attack on curl can in theory reach widely.

This is not paranoia. This setup allows us to sleep well at night.

This is why users still rely on curl after thirty years in the making.

Documented

I recently added a verify page to the curl website explaining some of what I write about in this post.

cURL and libcurl, Technology

One hundred weirdo emails

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  1. My email address is spelled out in the curl license
  2. The curl license appears in many products
  3. Some people have problems with their products and need someone to email
  4. A few of these discover my email in their product
  5. Occasionally, the person in need of help emails me about their product.
  6. I collect some of those and make them public

I hope I don’t have to spell it out but I will do it anyway: in these cases I don’t know anything about their products and I cannot help them. Quite often I first need to search around only to figure out what the product is or does, that the person asks me about.

Over the years I have collected such emails that end up in my inbox. Out of those that I have received, I have cherry-picked my favorites: the best, the weirdest, the most offensive and the most confused ones and I put them up online. A few of then also triggered separate blog posts of their own in the past.

They help us remember that the world is complicated and hard to understand.

Today, my online collection reached the magical amount: 100 emails. The first one in the stash was received in 2009 and the latest arrived just the other day. I expect I’ll keep adding occasional new ones going forward as well.

Enjoy!

cURL and libcurl

NTLM and SMB go opt-in

The NTLM authentication method was always a beast.

It is a proprietary protocol designed by Microsoft which was reverse engineered a long time ago. That effort resulted in the online documentation that I based the curl implementation on back in 2003. I then also wrote the NTLM code for wget while at it.

NTLM broke with the HTTP paradigm: it is made to authenticate the connection instead of the request, which is what HTTP authentication is supposed to do and what all the other methods do. This might sound like a tiny and insignificant detail, but it has a major impact in all HTTP implementations everywhere. Indirectly it is also the cause for quite a few security related issues in HTTP code, because NTLM needs many special exceptions and extra unique treatments.

curl has recorded no less than seven past security vulnerabilities in NTLM related code! While that may not be only NTLM’s fault, it certainly does not help.

The connection-based concept also makes the method incompatible with HTTP/2 and HTTP/3. NTLM requires services to stick to HTTP/1.

NTLM (v1) uses super weak cryptographic algorithms (DES and MD5), which makes it a bad choice even when disregarding the other reasons.

We are slowly deprecating NTLM in curl, but we are starting out by making it opt-in. Starting in curl 8.20.0, NTLM is disabled by default in the build unless specifically enabled.

Microsoft themselves have deprecated NTLM already. The wget project looks like it is about to make their NTLM support opt-in.

SMB

curl only supports SMB version 1. This protocol uses NTLM for the authentication and it is equally bad in this protocol. Without NTLM enabled in the build, SMB support will also get disabled.

But also: SMBv1 is in itself a weak protocol that is barely used by curl users, so this protocol is also opt-in starting in curl 8.20.0. You need to explicitly enable it in the build to get it added.

Not removed yet

I want to emphasize that we have not removed support for these ancient protocols, we just strongly discourage using them and I believe this is a first step down the ladder that in a future will make them get removed completely.

cURL and libcurl

bye bye RTMP

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In May 2010 we merged support for the RTMP protocol suite into curl, in our desire to support the world’s internet transfer protocols.

RTMP

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.

librtmp

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.

How about users?

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.

Compatibility

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.

When

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

cURL and libcurl

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.

Make it myself

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.

gnuplot

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!

Produce data to feed gnuplot

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.

The data

All data used for populating the graphs is open and available, and I happily use whatever is available:

  • git repository (source, tags, etc)
  • GitHub issues
  • mailing list archives
  • curl vulnerability data
  • hackerone reports
  • historic details from the curl past

Open and transparent as always.

Then it grew

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.

Graph 100

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.

Screenshot showing 100 graphs in the dashboard

Custom but available

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.

Data is knowledge

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.

The jokes

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.

Links

The git repository: https://github.com/curl/stats/

Daily updated curl dashboard: https://curl.se/dashboard.html

curl gitstats: https://curl.se/gitstats/

cURL and libcurl

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?

Trusting randos

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.

I reported this again

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.

“This is not a Microsoft problem”

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.

Outdated efforts

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.

How to address

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.

Conclusion

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.