HN.zip

GitHub RCE Vulnerability: CVE-2026-3854 Breakdown

382 points by bo0tzz - 78 comments
jfkimmes [3 hidden]5 mins ago
They hint at their AI-augmented reversing methodology, which demonstrates one of the core strengths of current LLM agents. These models, trained extensively on code, can immensely speed up the process of understanding complex system internals.

Security research historically has two difficult components that build on one another: 1. Understanding complex system internals: uncovering the inner workings hidden by abstractions or interfaces 2. Finding vulnerabilities in these uncovered mechanisms

Sometimes both steps are equally hard. But often, finding the vulnerability is trivial once the real mechanisms are uncovered, rather than relying on assumptions about inner workings.

CVE-2026-3854 is a case where the vulnerability is not plainly obvious after understanding the internals. Still, I am confident that this command injection would have been found quickly had it been exposed to a more traditional or accessible attack surface.

jcims [3 hidden]5 mins ago
Anyone in here work at Wiz? Seem like they do pretty good work. Tool itself has survived extreme growth/feature bloat and still does pretty well. Security team has found some really cool stuff.
az226 [3 hidden]5 mins ago
Lots of Unit 8200 peeps.
jospeh554 [3 hidden]5 mins ago
I'm not there, but we use it at our place. It triggers on entirely innocent things I do.

And yet when I do something a bit dodgy (like query a DC with a cli, and reset credentials) it's silent...

saghm [3 hidden]5 mins ago
> When babeld forwards a push request, one of the internal requests includes push options in the X-Stat header. Git push options are arbitrary strings that users can pass with git push -o. They are a standard git protocol feature, intended for server-side hints. babeld encodes them as numbered fields - push_option_0, push_option_1, and so on - alongside a push_option_count.

> babeld copies git push option values directly into the X-Stat header - without sanitizing semicolons. Since ; is the X-Stat field delimiter, any semicolon in a push option value breaks out of its designated field and creates new, attacker-controlled fields.

They managed to literally do the simplest possible thing wrong. The fruit was hanging so low it might have been underground.

irishcoffee [3 hidden]5 mins ago
Oh Bobby Tables, your mom was quite clever.
baccatore [3 hidden]5 mins ago
Why do they need to stir up needless fear by using words like "BREAKING", "unauthorized access", or "millions of repositories" about the vulnerability that they caught before it was exploited in their X.com?

https://x.com/wiz_io/status/2049153209982140718

philipwhiuk [3 hidden]5 mins ago
None of that is inaccurate? GitHub got lucky it was Wiz fuzzing them not state-sponsored agents?
bananapub [3 hidden]5 mins ago
> April 28, 2026

> GitHub Enterprise Server customers should upgrade immediately - at the time of this writing, our data indicates that 88% of instances are still vulnerable

> Upgrade to GHES version 3.19.3 or later

https://docs.github.com/en/enterprise-server@3.19/admin/rele... :

> Enterprise Server 3.19.3 - March 10, 2026

88% of on-prem customers haven't applied a critical security fix from 7 weeks ago, that seems ... bad.

semiquaver [3 hidden]5 mins ago
GHES is essentially unmaintained (perhaps “on life support” would be more charitable since they are certainly accepting payment for it) and has been so for about a decade. It requires a multi-hour downtime to apply even a patch-level release. They do not have any supported mechanism for HA upgrades. So even the most conscientious GHES customers lag the latest version because they can’t afford the downtime.

They are constantly telling all their GHES customers who complain about the severe flaws with the self-hosted appliance product to move to GitHub Enterprise Cloud, which is just regular GitHub.com, but who in their right mind would make that move nowadays??? At least GHES stays up during the daily github.com outages.

baby_souffle [3 hidden]5 mins ago
You can at least schedule the updates.

It's still a pretty annoying process, though.

semiquaver [3 hidden]5 mins ago
Until GHES can do zero-downtime upgrades nothing will get better. Not on their roadmap because as far as I’m aware the GHES team doesn’t actually exist or is entirely focused on KLTO. It’s a dead product that they wish didn’t exist.
everfrustrated [3 hidden]5 mins ago
Pretty sure GitHub Enterprise Cloud is just Github hosting their enterprise server for you on Azure so you don't have to do the patching yourself.
semiquaver [3 hidden]5 mins ago
It sure isn’t! GitHub Enterprise Cloud is simply an enterprise plan on the regular multitenant github.com. Your repositories are on disk right next to everyone else that uses github.com. There is no segregated storage or compute.

I wish they had a plan to literally host GHES for you because then more people in the company would be forced to reckon with how terrible GHES is from an operational perspective. It is stuck ca. 15-20 years ago conceptually.

js2 [3 hidden]5 mins ago
GHEC is a terrible fucking product too and for the life of me I don't understand why they didn't use subdomains to namespace customers from each other and from github.com.

It should be mycompany.github.com because the way it is now, we have to rename all our damn repo orgs as we move from GHES to GHEC ("github.com/mycompany-org/repo") which is no guarantee either because anyone could create that org before is. All sorts of terrible UX falls out from not having name-spaced the GHEC customers.

securesaml [3 hidden]5 mins ago
Github enterprise cloud is on github.com and with more features: http://github.com/account/enterprises/new

They don't host github enterprise server for you (though gitlab has something called gitlab dedicated which they host gitlab ee for you).

Kuinox [3 hidden]5 mins ago
Why is there an eu github status then ? https://eu.githubstatus.com/uptime
conception [3 hidden]5 mins ago
Data residency is a thing.
Kuinox [3 hidden]5 mins ago
And how would that explain the way higher SLA ?
brianmcnulty [3 hidden]5 mins ago
I assume a fair amount of these on-prem customers restrict access to their GHES instance to be behind corporate VPN or something similar and are planning a date to upgrade their instance that won't affect operations.

Any public instance should update immediately though, it's not very hard to put together how to repro the vulnerability on your own from what they provide in the article and the fact that GitHub Enterprise source is publicly available.

jamesfinlayson [3 hidden]5 mins ago
For sure - the last company I worked at that had GitHub Enterprise had it running on a private network only accessible within the company.
fastest963 [3 hidden]5 mins ago
Yeah, but this still gives any employee RCE on the GHES server right?
jamesfinlayson [3 hidden]5 mins ago
I suppose so. The company invested pretty heavily in security tooling, though I think it wouldn't have been hard to do something to bypass the security for internal servers.
technion [3 hidden]5 mins ago
I guess I woukd say youre fortunate to have not worked in a "we cannot use github.com because we take security very seriously" environment. Because always tells me you'll be running a on prem product that might get updated once a year.
eyegor [3 hidden]5 mins ago
On prem beats the heck out of github post Microsoft though... At least you know how to get it working again when someone breaks it. These days with github you expect a weekly 500, a rainbow unicorn error, build failures due to unavailable errors, etc. Last I checked the third party tracker github services were barely pushing one 9 of reliability.
bombcar [3 hidden]5 mins ago
If you're in the enterprise you can update something outside of the normal schedule and guarantee blow up everything (and be blamed) or you can stick with the schedule and hope for the best.

Guess which is usually picked ...

pixl97 [3 hidden]5 mins ago
Question is how fragile the upgrade process is in large installations. In other enterprise software messing around with large amounts of data I've seen the smallest things break the install and leaving the OPs team rolling back. Was like SharePoint in the past, you were rolling a dice when upgrading it.
chucky_z [3 hidden]5 mins ago
It's incredibly fragile. It breaks a vast majority of the time and takes multiple rounds of support on-call to upgrade typically.
formerly_proven [3 hidden]5 mins ago
Unsurprising for a fourth tier on-prem created by cutting a continuously deployed application into releases.
jamesfinlayson [3 hidden]5 mins ago
The GitHub blog had an article saying that all patches must pass for github.com before merge but the GitHub Enterprise tests have a three day window to be rectified.
angry_octet [3 hidden]5 mins ago
Another tour de force from Wiz, and a watershed moment in AI tooling enabling RE and compromise discovery.
avaer [3 hidden]5 mins ago
It throws a wrench into the argument of not publishing your source because AI will more easily compromise the code.

Another data point against doing security through obscurity.

latchkey [3 hidden]5 mins ago
People keep wanting to replace GitHub, but with what?

If GH is getting RCE's this late in the game who wants to take the chance something else won't?

skrrtww [3 hidden]5 mins ago
A "reasonable" answer is probably a primary self-hosted Forgejo instance as the canonical forge, while using GitHub as a mirror solely to take advantage of its free CI, while that lasts, while hosting secrets with a dedicated secret-hosting provider (I don't know what the provider du jour for this is these days).
latchkey [3 hidden]5 mins ago
Replace a whole 24/7 team of devops people with myself?

As much as I'd like to believe that I'm worthy, I'm not.

rnhmjoj [3 hidden]5 mins ago
It's the devops team can manage a measly 87% uptime [1] you're talking about, you can do a lot better on your homeserver.

[1]: https://mrshu.github.io/github-statuses/

skrrtww [3 hidden]5 mins ago
If the primary forge's only job is to host the actual Git infrastructure (the code, the MRs, the issues, maybe a wiki), it's a lot more simple than GitHub, and probably more within the scope of what people can reasonably administer themselves.
latchkey [3 hidden]5 mins ago
I hosted the first "java.apache.org". I was an early employee at CollabNet, and in the first discussions around starting subversion. I worked on Cloud Foundry.

This stuff isn't easy and I'm more than happy letting someone else do it at the expense of some downtime.

slopinthebag [3 hidden]5 mins ago
24/7 devops team for a forgejo instance? Come on mate...
latchkey [3 hidden]5 mins ago
24/7 devops team for github? Come on mate...
slopinthebag [3 hidden]5 mins ago
Is running a small forgejo instance for a team the same as running GitHub?
odie5533 [3 hidden]5 mins ago
Will I have to patch machines, keep packages updated, deal with SSL certs, maintain action runner infra, deal with billing for the machines, add monitoring, alerts, logging, etc

No, I don't want to be in the business of running my own Github clone. That's what I pay Github for.

Why do you pay salary to employees to buy food when you can just run a farm next to the office and save money by operating the farm and giving the employees food directly? You'd save money by not having to pay as high of salaries, and farms don't even need 24/7 devops teams.

altmanaltman [3 hidden]5 mins ago
Don't you think the farm example was a bit too extreme for it to make sense? A tech company probably does not have expertise in farming but devOps is something they already know how to do and can easily manage it in-house. Also how fast do you think farms produce food that you can drip feed it to employees constantly
embedding-shape [3 hidden]5 mins ago
> solely to take advantage of its free CI, while that lasts

Eh, if you want to be able to continue working, deploy and what not as normal during weekdays, I'd suggest also moving to Forgejo Actions if you're moving anyways. Not 100% compatible, but more or less the same, and even paying the same but with dedicated hardware you'd get way faster runners.

skrrtww [3 hidden]5 mins ago
For companies with resources for infrastructure, sure.

For OSS, the unlimited free minutes of multiplatform CI offered by GitHub are literally impossible to replace. Maintaining runners yourself to do the same things would be somewhere between a part- and full-time job.

embedding-shape [3 hidden]5 mins ago
> For OSS, the unlimited free minutes of multiplatform CI offered by GitHub are literally impossible to replace.

Yeah, how you think the ecosystem got by before GitHub even had actions? Y'all don't remember Travis CI et al anymore?

There are more CI services than what Microsoft offers the world, sometimes it's worth looking around a bit.

esseph [3 hidden]5 mins ago
> https://docs.codeberg.org/ci/

"Codeberg is a non-profit, community-led effort that provides services to free and open-source projects, such as Git hosting (using Forgejo), Pages, CI/CD and a Weblate instance."

Never say impossible.

Github is still "new" to a lot of us. OSS existed well before it, and will continue to exist well after.

skrrtww [3 hidden]5 mins ago
If Codeberg starts offering Mac and Windows runners alongside their Linux ones for free (or at an achievable price point) for a modest OSS project I'll certainly look at it very closely. If all I needed was a Linux runner, I'd probably be on there already.

And yes, if we make OSS just about hosting the code, things are much simpler. If you're a piece of desktop software though, and you have users, they'll typically (and reasonably) want auditable signed binaries on all the platforms you support, which requires multiplatform CI.

asa977 [3 hidden]5 mins ago
We moved from github to a self-hosted forgejo instance about 6 months ago, works like a charm. Still can't belive how snappy forgejo is / laggy github has become
latchkey [3 hidden]5 mins ago
Caligatio [3 hidden]5 mins ago
I am personally now drawing a clear delineation between projects for my internal consumption (e.g. ansible scripts) and projects that have potential use for the general populace. For the prior, I now host a private Forgejo instance. For the latter, I'll put it on GitHub but mirror it to my Forgejo instance.

I was pleasantly shocked that Forgejo is literally a single binary with a relatively easy config. All my internal services reference my Forgejo instance so, if I need to bail on GitHub, it's low friction for me.

crimsonnoodle58 [3 hidden]5 mins ago
Self hosted gitlab behind a VPN.

The all-in-docker image and a couple of gitlab runners is all small to medium sized teams need. (Don't overcomplicate it with the kubernetes version unless you really need it)

gtech1 [3 hidden]5 mins ago
GitLab ?
himata4113 [3 hidden]5 mins ago
Me and my friends call it CveLab because there was a time where there was a critical security update every week or multiple times a week.
latchkey [3 hidden]5 mins ago
The people who suggest gitlab, haven't used it. But I guess I could be tempted to try again...

https://status.gitlab.com/pages/history/5b36dc6502d06804c083...

capitalhilbilly [3 hidden]5 mins ago
If you could only choose from github, gitlab and atlassan then I suppose.. But really anything newer that stays in existance has to be focused on quality from early enough to not be defined by path dependence problems and bad choices like those 3.
latchkey [3 hidden]5 mins ago
Given that github is imploding under a lot of load, everyone leaving github for something else, actually makes github better.
gtech1 [3 hidden]5 mins ago
Ah, you assumed I meant SaaS GitLab. I meant the self-hosted version. I would never host our source code on a remote service.
latchkey [3 hidden]5 mins ago
Why not?
TZubiri [3 hidden]5 mins ago
just git
chucky_z [3 hidden]5 mins ago
.... git?

replace it with git.

if you want a whole ui you can use something like forgejo which has far fewer features likely leading to less issues.

debugnik [3 hidden]5 mins ago
You probably meant Forgejo. Codeberg is a Forgejo instance exclusive for FOSS projects.
latchkey [3 hidden]5 mins ago
i want what github offers.
heliumtera [3 hidden]5 mins ago
Enjoy your experience, there will certainly be no end to it.
latchkey [3 hidden]5 mins ago
I've had my account since 2008. ¯\_(ツ)_/¯

updated: changed the date to 2008.

my account shows 2001, but that's probably from projects I moved over... proof: https://github.com/lookfirst

necubi [3 hidden]5 mins ago
GitHub launched in 2008, so that seems unlikely?
seanclayton [3 hidden]5 mins ago
Just be careful your patronage doesn't lead to a sunk cost fallacy---a middle manager might just be betting on it
latchkey [3 hidden]5 mins ago
I have no ingrained loyalty, I just haven't found something better.
sitzkrieg [3 hidden]5 mins ago
i just deleted my account of 2008. github sucks
WASDx [3 hidden]5 mins ago
I was impressed enough by AI finding vulnerabilities in source code, but doing it in binary executables is just amazing. This has so much potential, good and bad.

And yet another lesson to not treat data as instructions. Sanitize all user input!

avaer [3 hidden]5 mins ago
Transformers were literally designed for translation.

As we have known for a while, they ended up being really good at translating source to source or text to source. It shouldn't be too surprising they are also really good at understanding the asm version too.

Doesn't make it any less impressive, but maybe less surprising.

halger [3 hidden]5 mins ago
Woah I wonder if they can tell if this has been exploited or not
semiquaver [3 hidden]5 mins ago
My read is that this vulnerability is exploitable by an anonymous user. They absolutely have HTTP/gitprotocol logs that would indicate whether this was exploited but if it was, they won’t have logging about what actually got accessed and who did it, since the exploit was capable of standalone execution on the git servers, which would by definition be capable of evading any logging.
formerly_proven [3 hidden]5 mins ago
This is just such an amateur hour vulnerability. Gluing strings together with no regard to what might be in them and then parsing them later...

edit: I didn't mean it as a put-down of either the article or how they found the vulnerability, but it wasn't a constructive comment either way.

dang [3 hidden]5 mins ago
It's good to add information about what the vulnerability actually was, but please don't do it in the key of putdown. We're trying for something else here.

https://news.ycombinator.com/newsguidelines.html

willworktill4pm [3 hidden]5 mins ago
GitHub case will be thought in schools how to screw up almost monopolistic position in the market in couple years. This is beyond bonkers.
hnlmorg [3 hidden]5 mins ago
Only if they take Skype off the syllabus first.
xaxfixho [3 hidden]5 mins ago
private equity: hold my beer!