GitHub RCE Vulnerability: CVE-2026-3854 Breakdown

(wiz.io)

370 points | by bo0tzz 19 hours ago ago

77 comments

  • jfkimmes 14 hours 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 16 hours 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 5 hours ago

      Lots of Unit 8200 peeps.

    • jospeh554 4 hours 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 9 hours 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 7 hours ago

      Oh Bobby Tables, your mom was quite clever.

  • baccatore 2 hours 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

  • bananapub 17 hours 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 15 hours 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 15 hours ago

        You can at least schedule the updates.

        It's still a pretty annoying process, though.

        • semiquaver 15 hours 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 14 hours 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 13 hours 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 6 hours ago

            [flagged]

        • securesaml 14 hours 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).

    • brianmcnulty 16 hours 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 10 hours 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 6 hours ago

          Yeah, but this still gives any employee RCE on the GHES server right?

          • jamesfinlayson 5 hours 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 9 hours 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 6 hours 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 16 hours 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 17 hours 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 17 hours 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 16 hours ago

          Unsurprising for a fourth tier on-prem created by cutting a continuously deployed application into releases.

          • jamesfinlayson 10 hours 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 13 hours ago

    Another tour de force from Wiz, and a watershed moment in AI tooling enabling RE and compromise discovery.

    • avaer 11 hours 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 18 hours 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 16 hours 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 16 hours 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 6 hours 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 16 hours 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 16 hours 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 12 hours ago

          24/7 devops team for a forgejo instance? Come on mate...

          • latchkey 11 hours ago

            24/7 devops team for github? Come on mate...

            • slopinthebag 11 hours ago

              Is running a small forgejo instance for a team the same as running GitHub?

              • odie5533 7 hours 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 7 hours 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 16 hours 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 14 hours 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 14 hours 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 10 hours 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 6 hours 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 10 hours 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

    • Caligatio 16 hours 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 12 hours 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 17 hours ago

      GitLab ?

      • himata4113 9 minutes 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 17 hours 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 15 hours 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 14 hours ago

            Given that github is imploding under a lot of load, everyone leaving github for something else, actually makes github better.

        • gtech1 11 hours 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.

    • TZubiri 13 hours ago

      just git

    • chucky_z 17 hours 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 17 hours ago

        You probably meant Forgejo. Codeberg is a Forgejo instance exclusive for FOSS projects.

      • latchkey 17 hours ago

        i want what github offers.

        • heliumtera 17 hours ago

          Enjoy your experience, there will certainly be no end to it.

          • latchkey 17 hours 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 17 hours ago

              GitHub launched in 2008, so that seems unlikely?

            • seanclayton 16 hours ago

              Just be careful your patronage doesn't lead to a sunk cost fallacy---a middle manager might just be betting on it

              • latchkey 16 hours ago

                I have no ingrained loyalty, I just haven't found something better.

            • sitzkrieg 12 hours ago

              i just deleted my account of 2008. github sucks

  • WASDx 16 hours 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 11 hours 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 15 hours ago

    Woah I wonder if they can tell if this has been exploited or not

    • semiquaver 15 hours 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 15 hours 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.

  • willworktill4pm 17 hours 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 16 hours ago

      Only if they take Skype off the syllabus first.

      • xaxfixho 16 hours ago

        private equity: hold my beer!