The pressure | daniel.haxx.se

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I’m doing Open Source primarily because I love it. The social aspects, the for-the-good angle and for the challenge of engineering this to work for everyone. I also do it because it is my full-time job and getting food on the table and provide for my family is not unimportant. It may come as a shock, but I am not in this game for the money or the extravagant life style.

I have been working full-time on curl since 2019. For me, this typically means doing 50 hour work weeks, as I spend all days on it and then I top them off with a few more hours every late night – all days of the week, I spend all this time on curl because it is a work of love and it is both my job and my spare time hobby and no one counts my hours anyway. (And no, I do not recommend anyone else to do the same. I’m not suggesting this for others.)

I consider my primary work-related mission in life to be to make curl the best transfer library and tool possible and make it qualify as a top project in Open Source, quality, performance and not the least, security. I believe we generally meet these lofty goals.

I founded the curl project, I am still a lead developer in the project almost thirty years later. While I always clearly state that curl is not a one-man shop and that curl would absolutely not be what it is without my awesome curl team mates, a large part of the world still thinks of curl as my project and sometimes more or less equals curl with my person.

I cannot help to take curl issues personally. When someone critiques curl, it is by extension a complaint on decisions and choices I stand by and behind – and many cases I made the calls. curl is personal to me. curl has formed my life forever.

I have two kids. They were both born many years after I started working on curl and they are both adults and independent individuals now. I love them dearly. Life passes by but curl remains. We’ve had slow times and busy times. The decades pass.

Later this year the curl project celebrates thirty years. We typically repeat that the number of curl installations in the world is perhaps thirty billion.

Things changed

Over the last years I have done numerous blog posts on the state of security reports submitted to curl. They have gradually switched over from complaints on stupid LLMs, to stupid AI slop reports, closing the bug bounty over to the current high quality chaos which for us started maybe at some point in March 2026.

We have seen many spectacular security failures through the years, in Internet products, in software infrastructure and in Open Source. Every time we read about those events, we get reminded about how curl is everywhere and how we really really really do not want anything such to happen to us or our users. And we take another lap around the project, tighten every bolt a little more, add a few more checks, tests and guidelines to ideally make the curl ship ever so slightly less likely to ever leak or sink.

Scrutinized

Recently, after I pointed out that Mythos only found a single low severity problem in curl in its first scan, countless people have repeated the claim that curl is one of the most scrutinized, most reviewed, most fuzzed and most verified source codes you can imagine. Perhaps that’s true, but I just want to mention this: that’s not by mistake. That’s not an accident or a happy circumstance. That’s the result of relentless work and attention to details through decades. Software engineering done right. Iterative improvements over time that simply never ends is an effective method.

This does not however mean that we don’t have bugs or that we don’t have security problems left, because we do. We have hundreds of thousands of lines of source code that is doing highly parallel networking for many protocols on all imaginable operating systems and CPU architectures – in C. So we fix the problems, patch them up and ship new releases. Over and over.

Thirty billion installations world-wide means that everyone reading this blog post has curl installed multiple times in stuff they own. In phones, tablets, cars, TVs, printers, game consoles, kitchen equipment and more. Not to mention all the online digital services we use and those devices communicate with. I cannot stress the importance of curl security and I would guess that most of you agree with me.

I am jealous of those projects that shipped a horrible bug at some point in the past that made the world burn for a while. They got attention and some of them then got funding and financial muscles to get them staff and hire multiple full time engineers. I sometimes think we would be better off if we also had one of those.

Never-before experienced

A thirty years old project could make you think you’ve seen most things already, but we have not been in this situation before.

The rate of incoming security reports is 4-5 times higher than it was in 2024 and double the speed of 2025 – meaning that on average...