Awesome find by https://hackerone.com/joaxcar and it's a little bit frightening that this severe of a bug isn't the biggest security vulnerability of today
This seems super light on details and I had to dig to find more information. We don't use Gitlab, but we do use Ruby, so I was worried we might be impacted.
So the problem is in Ruby itself? Not in onigmo, or in oniguruma? If simply updating Ruby fixes the problem... is GitLab vendoring a Ruby runtime or something? Or has Ruby not published this fix yet?
… Or is the GitLab/onigmo bug about failing to escape regex input?
At least second regex related CVE in GitLab in the past few weeks. Awful to see that the endpoint is reachable unauthenticated, but I'm glad that they provide guidance in how to check the logs for attempts of exploitation
As far as I can tell, it requires forcing GitLab to render a malicious org-mode file. I don't really see a way to do that without authenticating and uploading one. Am I missing something?
Back in perl 5.8 and older, the regex engine worked by recusing at the level of C functions, and so you could trigger stack overflows by giving it large strings.
Is this similar?
I wonder why gitlab even has its own regex compiler. Or is this a vulnerability in an underlying library or programming language?
This is shaping up to be the single worst security news day ever. Given the role that AI played in some of the discoveries, one has to wonder if this marks the start of some dark age of IT security.
Maybe I'm not enough in the weeds to see it as much, but the last few months seem to have been a much slower trickle of "how did we not catch this" exploits, while they are now appearing with much more sophisticated (though still usable in practice) exploit chains on much larger target codebases.
The last few months seem to have been a lot more imunder control with also the frontier labs more warning of "what happens when Mythos-class model get in the hands of everyone" than that actually becoming reality. Now, it appears to be actuually turning into reality.
The problem is fixing the bug and not only fixing the code, but applying the fix in production in a timely manner and without interrupting the business.
I think this marks the beginning of the golden age. Investments in automated agent driven security scans on all software is coming to every business. Software and infrastructure will become more secure than ever before.
I also hope that we come out in a golden age, but we are very much in for a rough few months/years where all the low hanging fruit is being picked up until we end up with much more hardened systems.
It's ok, we'll just point more LLMs at the new code and the problem will fix itself. In the mean time can we unplug the ethernet cable from the nuke silos for a while?
Gitlab is probably more prominent since it's a large enterprise piece of software that's self hosted. Every bug in a library used by Gitlab becomes a problem for Gitlab. While hosted platforms like Github can just update the library and not have to make an announcement.
Years ago I worked at a company that had a nightly cronjob for yum to apply security updates (with a couple of important exceptions that were handled manually). Always seemed very iffy to me for such a big company where downtime was very expensive.
No. Like the PHP vulnerability, this was a bug in a language interpreter written in C, and a bug that would not be possible in most newer languages. Even as secure-by-design becomes more prevalent, there will be vulnerabilities, but this one is a taste of the past.
GitLab has remediated an issue that, under certain conditions, could have allowed an unauthenticated user to execute arbitrary code on the GitLab server due to integer overflow when compiling a specially crafted regular expression. (...)
Truth be told, I don't think that "GitLab Critical Patch Release: 19.5.1, 19.4.3, 19.3.6, 19.2.9, 19.1.9, 19.0.10, 18.11.13" is a more descriptive title, even taking the HN guidelines into account. It could be better, sure, but it's not horrible (IMO).
It's an editorialization. The submitter is saying something about the importance of CVSS that the article does not. A better title would say "Remote Code Execution" where it says "CVSS 10.0" now.
No? CVSS is a Ouija board. Citrix directory traversal got scored 10.0. So did a Cisco Broadworks SSO bypass. Meanwhile, Shellshock did not.
CVSS is like the Pitchfork Music ratings scale. It communicates false precision, and it's easy to point to places where that precision misleads (D-plan's "Emergency & I" is not better than every Yo La Tengo album).
Have you read signal/noise theory? That a signal isn't perfect (that it contains false positives or positive falses in case of binary signals, or that it has a delta between the signal and the underlying phenomenon) doesn't mean that it carries no information.
For example if I cry wolf 50% of the time, but 100% of the times there's a wolf I cry wolf. Then no matter what the frequency of wolf sightings are, my crying wolf carries some information (unless there's always a wolf). Assume there's a wolf 1% of the nights, then I will cry wolf 50% of the time, and you only need to check for a wolf 50% of the nights rather than 100%.
It's worth noting that there's still technically signal even if I sometimes miss a wolf, even if you may choose to ignore that signal in order to pursue 100% accuracy yourself.
It's more like: you work as an animal spotter, and if you tell people you saw a hamster, you'll get no glory. So obviously you spotted a direwolf at least 12 feet tall.
Interestingly CVSS was designed to help with this specific issue. You are complaining that the system is imperfect, but you fail to imagine how it works without such a system, everyone tagging their issue as critical.
I am concerned for my self hosted servers, well only hope is tailscale should be entirely secure, and egress is filtered heavily... If that doesn't work my home lab is fucked.
Any suggestions folks, not even my terminally online self can handle all of these.
Awesome find by https://hackerone.com/joaxcar and it's a little bit frightening that this severe of a bug isn't the biggest security vulnerability of today
It’s the 2020s baby, this one is lucky to break the top 3!
Give it an hour or so and there will be a bigger one.
This seems super light on details and I had to dig to find more information. We don't use Gitlab, but we do use Ruby, so I was worried we might be impacted.
This is the best overview I found: https://lilting.ch/en/articles/gitlab-cve-2026-110264-org-mo...
The bottom line: this is an issue in Ruby's regex engine, which was fixed in April and backported recently. [1]
Everyone running applications where attacker-controlled input might find its way (unescaped) into Ruby regexes is vulnerable to remote code execution.
[1]: https://github.com/ruby/ruby/pull/16801
So the problem is in Ruby itself? Not in onigmo, or in oniguruma? If simply updating Ruby fixes the problem... is GitLab vendoring a Ruby runtime or something? Or has Ruby not published this fix yet?
… Or is the GitLab/onigmo bug about failing to escape regex input?
At least second regex related CVE in GitLab in the past few weeks. Awful to see that the endpoint is reachable unauthenticated, but I'm glad that they provide guidance in how to check the logs for attempts of exploitation
As far as I can tell, it requires forcing GitLab to render a malicious org-mode file. I don't really see a way to do that without authenticating and uploading one. Am I missing something?
"Can hold"? Meaning the attacker needs push access to a public repo?
Is this a bug in GitLab or in Ruby? It's hard to tell from the report and the patch...
Possibly a backport of https://github.com/ruby/ruby/pull/16801
The module in that diff being called "onig" is quite unfortunate, the error codes look like a slur.
Or Rails...
If you're patching a fleet, gitlab-rake gitlab:env:info gives you the exact version per node, faster than guessing from the omnibus package name.
Back in perl 5.8 and older, the regex engine worked by recusing at the level of C functions, and so you could trigger stack overflows by giving it large strings.
Is this similar?
I wonder why gitlab even has its own regex compiler. Or is this a vulnerability in an underlying library or programming language?
Looks like Gitlab ships its own forked copy of the Ruby Onigmo regex engine.
Why? Is/was Ruby vulnerable?
This is shaping up to be the single worst security news day ever. Given the role that AI played in some of the discoveries, one has to wonder if this marks the start of some dark age of IT security.
This has been going on for months actually with no end in sight.
Maybe I'm not enough in the weeds to see it as much, but the last few months seem to have been a much slower trickle of "how did we not catch this" exploits, while they are now appearing with much more sophisticated (though still usable in practice) exploit chains on much larger target codebases.
The last few months seem to have been a lot more imunder control with also the frontier labs more warning of "what happens when Mythos-class model get in the hands of everyone" than that actually becoming reality. Now, it appears to be actuually turning into reality.
It depends on the net rate of new bugs being made vs the bugs discovered and fixed. Hopefully AI can find bugs faster than new ones are being created.
The problem is fixing the bug and not only fixing the code, but applying the fix in production in a timely manner and without interrupting the business.
I think this marks the beginning of the golden age. Investments in automated agent driven security scans on all software is coming to every business. Software and infrastructure will become more secure than ever before.
I also hope that we come out in a golden age, but we are very much in for a rough few months/years where all the low hanging fruit is being picked up until we end up with much more hardened systems.
Why would it be more secure if there is even more investment in automated agent driven insecure code generation that can outpace any scan capacity?
If catching "all" security issues becomes feasible then the balance tilts in favor of the projects vs the attackers.
Big malicious entities always had more investments in this than random open source projects.
Since you need an unrealistic if, I presume you agree that the balance doesn't shift?
> the single worst security news day ever
I'd say, the single worst security news day for now
Attack Tokens versus Defense Tokens has already been the norm for the past 2 years. AI is just that good at this game.
It's over. Cybersecurity is now Yugioh, where the lifepoints is your token budget.
What? More like a golden age of security. AI is ripping the bandaid off right now. At the end of this software is going to be a lot more secure.
That's where we will end up, but the in between time is the worst time ever for trying to secure an internet connected computer.
> At the end of this software is going to be a lot more secure.
Can I get that in writing?
As we speak more slop is added to the pile, far more than can reasonably be reviewed and a lot of that code will be insecure.
It's ok, we'll just point more LLMs at the new code and the problem will fix itself. In the mean time can we unplug the ethernet cable from the nuke silos for a while?
Priorities... you are right.
Did you go to sleep in 2015 and then wake up just now in 2026?
Buckle up
possible bug? or too soon to check? :)
after updating a pop-up still shows:
"You are currently on version 19.5.1! We strongly recommend upgrading your GitLab installation immediately."
while 19.5.1 should be the latest and fixed version
Their update checker has never worked very well. It takes hours to stop getting the upgrade warning inside of the GitLab dashboard.
I have that aswell…
But I also updated pretty early.
same here, but with 19.4.3
What a great week security wise!
Lemon, it's wendesday
I picked the wrong week to stop drinking coffee.
I picked the wrong week to quit sniffing glue.
You should go backto the glue it’s not a good idea to be normal about this. We should all be sniffing glue Charlie day style
I picked the wrong week
It's only Wednesday, plenty of week to go.
Sir, it is only wednesday
You spelled Wendy's wrong.
Gitlab has had a lot lately. I’ve had to patch every other week for the last few months
Gitlab is probably more prominent since it's a large enterprise piece of software that's self hosted. Every bug in a library used by Gitlab becomes a problem for Gitlab. While hosted platforms like Github can just update the library and not have to make an announcement.
And it's not even written in C! /s
Using AI agent to apply patches & upgrade is now mandatory to keep up with the pace.
Dont even need "AI" for that. Just renovate.
Cross your fingers and pucker your butt that it doesn't fuck it up.
Years ago I worked at a company that had a nightly cronjob for yum to apply security updates (with a couple of important exceptions that were handled manually). Always seemed very iffy to me for such a big company where downtime was very expensive.
Good luck with the security and the stability of a system managed like this.
is this a taste of things to come?
No. Like the PHP vulnerability, this was a bug in a language interpreter written in C, and a bug that would not be possible in most newer languages. Even as secure-by-design becomes more prevalent, there will be vulnerabilities, but this one is a taste of the past.
The critical CVE (https://docs.gitlab.com/releases/patches/patch-release-gitla...) seems embargoed, just saying that it involves integer overflow in a regex compiler.
Coincidentally, there is also a (non-embargoed) musl libc CVE published today involving integer overflow in its regex compiler: https://www.openwall.com/lists/musl/2026/10/21/1
Perhaps that is the underlying bug, or a similar one turned up by the same security research?
"CVSS 10.0" isn't in the headline here and a CVSS of 10 doesn't actually mean anything.
Deeper in the article: https://docs.gitlab.com/releases/patches/patch-release-gitla...
GitLab has remediated an issue that, under certain conditions, could have allowed an unauthenticated user to execute arbitrary code on the GitLab server due to integer overflow when compiling a specially crafted regular expression. (...)
CVSS 10.0 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H)
Here, CVSS 10.0 means arbitrary remote code execution.
"Arbitrary RCE" does mean something. "CVSS 10.0" does not. We should be using the article headline here.
Truth be told, I don't think that "GitLab Critical Patch Release: 19.5.1, 19.4.3, 19.3.6, 19.2.9, 19.1.9, 19.0.10, 18.11.13" is a more descriptive title, even taking the HN guidelines into account. It could be better, sure, but it's not horrible (IMO).
It's an editorialization. The submitter is saying something about the importance of CVSS that the article does not. A better title would say "Remote Code Execution" where it says "CVSS 10.0" now.
Good point guys, I've updated the title.
Because "10 out of 10" is a better headline for the average reader than "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H".
Sometimes CVSS 10 "oversells" the true severity of a bug but this doesn't seem to be one of those cases.
>CVSS of 10 doesn't actually mean anything.
Might you perchance be exaggerating?
No? CVSS is a Ouija board. Citrix directory traversal got scored 10.0. So did a Cisco Broadworks SSO bypass. Meanwhile, Shellshock did not.
CVSS is like the Pitchfork Music ratings scale. It communicates false precision, and it's easy to point to places where that precision misleads (D-plan's "Emergency & I" is not better than every Yo La Tengo album).
Have you read signal/noise theory? That a signal isn't perfect (that it contains false positives or positive falses in case of binary signals, or that it has a delta between the signal and the underlying phenomenon) doesn't mean that it carries no information.
For example if I cry wolf 50% of the time, but 100% of the times there's a wolf I cry wolf. Then no matter what the frequency of wolf sightings are, my crying wolf carries some information (unless there's always a wolf). Assume there's a wolf 1% of the nights, then I will cry wolf 50% of the time, and you only need to check for a wolf 50% of the nights rather than 100%.
It's worth noting that there's still technically signal even if I sometimes miss a wolf, even if you may choose to ignore that signal in order to pursue 100% accuracy yourself.
It's more like: you work as an animal spotter, and if you tell people you saw a hamster, you'll get no glory. So obviously you spotted a direwolf at least 12 feet tall.
Interestingly CVSS was designed to help with this specific issue. You are complaining that the system is imperfect, but you fail to imagine how it works without such a system, everyone tagging their issue as critical.
CVSS is good, it's better than nothing.
I am concerned for my self hosted servers, well only hope is tailscale should be entirely secure, and egress is filtered heavily... If that doesn't work my home lab is fucked.
Any suggestions folks, not even my terminally online self can handle all of these.
I recently jammed all my stuff behind Tailscale. I sure hope that doesn't burn me.
But it's a lot better than having things live on the open internet!
Also looking at those old C++ services a whole lot differently now.
Yup just going through the anxiety here. I even self-host my personal e-mail! This is not going to end well.
I have renovate set to automerge gitlab patch releases
as a fellow self-hoster, this is a rough time to be us