You should change the URL to https://codeberg.org/forgejo/forgejo/milestone/139655

> PR: Critical: fix: prevent template expansion from interfering with git repo initialization. When generating a new repository from a template repository, Forgejo clones the template repository, removes the .git folder, performs variable template expansion on files listed in .forgejo/template, and initializes a new git repository. During this process, variable template expansion could be misused in order to create a new .git folder, which git would adopt and incorporate during its initialization of a new git repository. A malicious template repository could be used to read arbitrary data from the Forgejo host, and to execute arbitrary processes on the Forgejo host, as a remote code execution attack. To address this issue, after variable expansion is completed, any existing .git folder is removed from the directory before the git repository is initialized.

Conciser: User's who can create new repositories, can exploit templates to do variable template expansion leading to being able to read arbitrary data from the Forgejo hosts.

If you have open registrations or otherwise users you don't 100% trust with the ability to create new repository (which is the default I think?), they could potentially exploit this and you probably wanna upgrade ASAP.

If you have only trusted users, or single user, seems it's fine. Of course, wanna upgrade anyway to not add escalation paths, but in the other situation it's graver.

> To address this issue, after variable expansion is completed, any existing .git folder is removed from the directory before the git repository is initialized.

What happened to sandboxing the offending git invocation?

Only posting here because I've been asked about it. Gitea is protected against both of these issues.

(bias note: part of project leadership of Gitea)

Edit: As a note, security incidents happen to everyone and we shouldn't shame anyone for reporting them, especially as that'd otherwise cause less issues to be reported overall.

> Gitea is protected against both of these issues.

Is Gitea's immunity just incidental because it was written by a different person, or is it due to a deliberate defensive system that prevents such bug/mistake from occurring?

Very interested in knowing too, since the issues seems to not be related at all, or similar, so now this must mean a Gitea "project leader" would only say this if they have some sort of layer that doesn't require them to manually patch issues individually. Meaning, firewall? Would be weird if that's built-in into Gitea though... Hmm.

It looks like Gitea made the same fix (rm -r .git after template processing) back in February: https://github.com/go-gitea/gitea/commit/2176e84ab977011ff2b...

PR: https://github.com/go-gitea/gitea/pull/36734

So likely Gitea < 1.25.5 was vulnerable.

i like how this is a side effect of a bunch of assorted changes in a commit and PR solely described as "Fix path resolving" making it hard for anyone running Gitea to even know this is a security fix

It’s explicitly listed as a security fix in the release notes, accompanied by a CVE: https://blog.gitea.com/release-of-1.25.5/

It is unfortunate nobody tipped anyone off downstream.

Forgejo is a fork of gitea.

Hence the question...

Your note is really important! Thanks for adding it. None of us are perfect.

This was my first thought after they disallowed LLM contributions.

They may not use AI to check for vulnerabilities but attackers are going to which puts themselves at the disadvantage.

They did not disallow LLM contributions, and they definitely didn't disallow using LLMs to research security vulnerabilities. They only disallowed projects that are majority LLM-written.

https://codeberg.org/Codeberg/org/commit/71149c7fc95ccfeae36...

That is about Codeberg, not Forgejo.

Forgejo disallows LLM contributions, including using a "general AI" (they include LLMs under "general AI") for reviews[0]:

> 5. Using general AI for review is forbidden. If the change contains changes to the UX it has to be approved by a human reviewer.

[0] https://codeberg.org/forgejo/governance/src/branch/main/AIAg...

Ah sorry, didn't realize they had their own policy. This is a little stronger, but you can certainly still use an LLM to search for vulnerabilities, you would just need to write fixes yourself and mention if you used an LLM for assistance.

The rule you quoted is about code reviews, they don't want you using an LLM to write reviews or leave comments.

This is a pretty poorly written policy to be honest, so I understand if you interpret it to mean "no LLMs in any capacity", but I think if that's what they meant they would have said that. In fact they explicitly allow content "made with the help of AI", you just have to disclose it.

Their definition of vibe coding is pretty whacky.

>Vibe coding is the practice where AI creates a code change (feature, bug fix, tests, refactor) with a human that describes what needs to be implemented.

So if you let an AI prompt another AI without human input, that's not vibe coding? Meanwhile if you prompt the model with pseudo code you've written or code written in another programming language to translate into the target language, that's vibe coding?

>It is not allowed to use AI in an autonomous-looking way to contribute in Forgejo.

They used the word "in", meaning it could refer to organizational membership, their repo or theoretically any instance of Forgejo, including self hosted ones. They failed to specify what part of Forgejo or the definition of Forgejo they meant.

Overall this is a pretty poorly written document and when you think about it, it doesn't really matter how poorly written it is when they are basically 100% against AI.

> Forgejo disallows LLM contributions

You're misreading the rule.

>> 5. Using general AI for review is forbidden.

The second sentence makes it even clearer, as it would have been unnecessary under a blanket ban scenario

>> ... If the change contains changes to the UX it has to be approved by a human reviewer.

This looks unambiguous to me:

  > Forgejo does not accept works of authorship (code, documentation, etc.) either partially or completely generated by AI due to legal uncertainties.

Using AI to find a vulnerability is not a work of authorship. Using the AI generated text as your bug report would be, but if you use AI to find a bug, then write up a report yourself, I think that would be fine.

>If the change contains changes to the UX it has to be approved by a human reviewer.

Would that not imply that a change that does not effect the UX does not have to be approved by a human reviewer? Otherwise, why specifically call out "changes to the UX" and not say "all changes"?

I really disagree with their acceptable usage policy, but you can't say it with certainity that LLM contributions would be a fix for this. They generate so much noise (as the primary incentive behind an independent LLM scan is often cheap contributor brownie points for your CV) that it also could lead to bogus PRs being approved or helpful PRs being lost in the noise.

Why can't you use an LLM to find vulnerabilities and then hand-code the fix? You don't even have to clean-room implement it; let the LLM write the code, and then reimplement, doing what you can to de-LLM-ify it.

You can. People on Codeberg use LLMs. They are just against spam of low quality projects generated with LLMs.

Do you expect it to be enforced by a machine? Why would you need a precise definition of "majority"?

You can, though some people are going to be annoyed by it and just publish a zero day out of spite.

Was this discovered by AI? Is all AI code 100% free of bugs?

You are implying that just by allowing LLM contributions your product is free of bugs, and the LLM won't introduce new bugs. Of course, if the LLM introduces bugs, the solution is to add another layer of LLM looking for bugs, ad infinitum.

Another post from today from Shopify, praising LLM to code their frontend, also stated that their LLM generated code is not ready to deploy, and needs to be reviewed:

> It’s tempting to just point an LLM to the React Native codebase and try to one-shot the same features in native, but it doesn’t work. Even if you ask it to gather as much information as it can up front, freeze that into specs, task files, and then implement it, you end up with a huge amount of unmaintainable code that can’t be shipped. [...] each [build] must prove its behavior with tests, match the running app in a visual review, survive two adversarial code reviewers, and get a human's nod before it's committed and the next one starts.

> You are implying that just by allowing LLM contributions your product is free of bugs

That... is not the implication of the comment you're replying to.

You don't need to make it all fundamentalist.

> They may not use AI to *check for vulnerabilities*

you didn't read the comment, did you?

Disallowing LLM contributions doesn't disqualify the use of LLMs to identify vulnerabilities.

Removing .git after expansion seems fragile. Sandboxing the git step would close the whole class of bugs.

Since the release notes is currently unreadable due to codeberg rate limits, the two fixes in the release notes are:

https://codeberg.org/forgejo/forgejo/pulls/14301:

*Critical:* fix: prevent template expansion from interfering with git repo initialization. When generating a new repository from a template repository, Forgejo clones the template repository, removes the `.git` folder, performs variable template expansion on files listed in `.forgejo/template`, and initializes a new git repository. During this process, variable template expansion could be misused in order to create a new `.git` folder, which git would adopt and incorporate during its initialization of a new git repository. A malicious template repository could be used to read arbitrary data from the Forgejo host, and to execute arbitrary processes on the Forgejo host, as a remote code execution attack. To address this issue, after variable expansion is completed, any existing `.git` folder is removed from the directory before the git repository is initialized.

https://codeberg.org/forgejo/forgejo/pulls/14301:

ensure authorization reducer is accessed when checking editable PRs in APIs. When editing a git repo contents through Forgejo's API, a specialized security control is used to permit repository maintainers to edit branches that they do not own when an open pull request with the "allow maintainer edit" option is present. This specialized security control did not take into account API-specific security restrictions, such as repo-specific access tokens. As a result, it was possible for an API access token with restricted permission to make modifications outside of that restricted permission. The specialized security control has been updated to take into account API authentication security restrictions.

---

So if like me you run a private forgejo instance with closed signups and limited repository creation, you can wait for the update. Otherwise maybe take it off the public internet for a bit?

Relevant change:

   Security bug fixes

    PR: Critical: fix: prevent template expansion from interfering with git repo initialization. When generating a new repository from a template repository, Forgejo clones the template repository, removes the .git folder, performs variable template expansion on files listed in .forgejo/template, and initializes a new git repository. During this process, variable template expansion could be misused in order to create a new .git folder, which git would adopt and incorporate during its initialization of a new git repository. A malicious template repository could be used to read arbitrary data from the Forgejo host, and to execute arbitrary processes on the Forgejo host, as a remote code execution attack. To address this issue, after variable expansion is completed, any existing .git folder is removed from the directory before the git repository is initialized.

It looks like this is a bit less concerning if you have turned off open account registration.

``` This git endpoint is seeing a high influx of requests for this repository, to preserve the availability of Codeberg your search request will not be processed. Sorry for the inconvenience and please try again later. ```

Any mirror?

The PR is still accessible https://codeberg.org/forgejo/forgejo/pulls/14300

    Critical: fix: prevent template expansion from interfering with git repo initialization. When generating a new repository from a template repository, Forgejo clones the template repository, removes the .git folder, performs variable template expansion on files listed in .forgejo/template, and initializes a new git repository. During this process, variable template expansion could be misused in order to create a new .git folder, which git would adopt and incorporate during its initialization of a new git repository. A malicious template repository could be used to read arbitrary data from the Forgejo host, and to execute arbitrary processes on the Forgejo host, as a remote code execution attack. To address this issue, after variable expansion is completed, any existing .git folder is removed from the directory before the git repository is initialized.

Wonder how long it took from report to patch. IME codeberg has one of the rudest security teams in oss (fair enough or not, irrelevant). https://news.ycombinator.com/item?id=47941590 Is quite relevant

Is that linked submission "your experience" or is there something else you're basing that on? Because that article you linked is kind of strange, read through the comments on what you linked.

Forgejo's security team received disclosure of this issue on September 4th. (source: I am a member of that team)

(Thanks for your work!)

For those on version 15 LTS, this fix was released with v15.0.8.

Updated mine now. The release notes[0].

0. https://codeberg.org/forgejo/forgejo/src/branch/forgejo/rele...

This is why I prefer simpler setups for personal use/hosting. Something like cgit that has no accounts has much less surface area for this kind of issue.

The opex and security fine costs of moving off managed services like GitHub/GitLab are catching up.

The amount of time I need to spend maintaining my Forgejo instance this year, even after accounting for this RCE, has been less than the amount of time GitHub has been degraded or unavailable this year.

This vulnerability, which doesn’t affect my installation, would take approximately 5 minutes to patch if it did. With that exception, my server will have had approximately 99.999% uptime over the last several years.

It would take a boatload of such events to equal the opex of GitHub hosting. That’s not an excuse to run amok, but it’s far from tipping the scales in GitHub’s cost favor.

Yep. I have one hanging off an openbsd machine on a tailnet, took me like... 5 minutes to update it, and it's not exactly a common setup...

Wouldn't most users considering or using Forgejo also have considered (or used) self-hosted Gitlab which would have the same opex / security costs (and much higher hardware requirements)?

If you are self-hosting Forgejo and haven't done it yet, consider creating a Codeberg account and following https://codeberg.org/forgejo/security-announcements/issues

They also have a releases RSS feed. I have those in my mail client (Thunderbird) directly for the projects that I must closely follow critical updates of.

What does the error message mean by "Your search request"? Why is viewing a single file in a repository considered a search request? That smells like poor caching somewhere

Can't load the page but hopefully it's on an endpoint sitting behind my Tinyauth protection.

Glad I have my Forgejo service set to auto update.

Quick note that this is not an RCE in the typical sense that I can rock up to a Forgejo installation and execute code on the server. The attack vector here is via a template repo specified when initializing a new repo. The template repo could contain malicious code that then executes on the host server. So if you don't create new repos from mystery meat template repos, you should be ok.

Are you sure? The change says "A malicious template repository could be used to read arbitrary data from the Forgejo host" (emphasis added). Couldn't an attacker create a template repo and then immediately create a new repo from their own template, causing the Forgejo process to execute their template code on the server?

They could, and this is definitely a RCE (a Remote Code Execution) vulnerability. GP confusion stems from the fact, that you (the forgejo user) must execute this attack on "your" instance. But of course the problem is that forgejo user can, in fact, be malicious, and use this vulnerability to escalate their priviliges from user to server.

It can't be done without authenticating first, but there's nothing about RCE that says that it must be sent from unauthenticated connection.

Would be good to label it "authenticated RCE" to make this clear

>So if you don't create new repos from mystery meat template repos, you should be ok.

You should be OK, but if attacker takes over your user (or any user in your forgejo instance) they can execute code on the host server - as you said yourself. In other words, it allows them to achieve remote code execution, so it's a RCE.

Trying to open any codeberg.org page from my main Helium browser results in a 403 just saying "Bye". Opening in Chrome or Firefox works fine. Very confusing.

As I said before for patching vulnerabilities in the age of AI [0], attackers are going to build exploits around this RCE with AI or even find more flaws with AI.

This means you have no choice but to use AI to defend, find and patch these flaws before attackers quickly build and use these exploits to target users.

You cannot afford to disallow or have a 100% ban on LLM contributions while attackers do not care and will use AI to find the flaws and attack you faster than you can triage it.

[0] https://news.ycombinator.com/item?id=49262849

If nothing else having AI review anything security related may be a good idea.