Carrot Disclosure: Forgejo

https://dustri.org/b/carrot-disclosure-forgejo.html

by bo0tzz • 3 months ago

145 58 3 months ago

dangus3• 3 months ago

The author's attitude is so off-putting. What gives? Did Forgejo hurt you?

The Forgejo disclosure process looked pretty simple and straightforward to me. The bold and all-caps words that bothered the author are just making sure you know how to disclose vulnerabilities safely without leaking zero-day exploits to a wider audience than necessary.

I'm also not impressed with a carrot disclosure that looks like this. Running a python script to compromise a locally hosted instance? Bruh, you have physical hardware and host shell access. That python script could be doing anything including running as root.

Show us the exploit hitting a remote server.

shimman2• 3 months ago

Seriously, this author comes across as an absolute sore loser if this is the PR they are referring too:

https://codeberg.org/forgejo/forgejo/pulls/12283

Someone asking you to write a test for new code and then making this blog in response is just so pathetic.

onedognight• 3 months ago

To hell with writing a test for you. That’s what you say to someone who gets paid by you. If the project doesn’t want the fix. That’s their issue, not the reporter’s.

martey• 3 months ago

While I agree with you that this blog post (and the "carrot disclosure" described in it) is ill-considered, the pull request is not really "new code", it adds quotes to HTML attributes that are missing them. I think it's entirely reasonable for a contributor to assume that a new test case would not be needed for this small change, and that the maintainer's response ("So a simple question: is this code covered under a test? If not, you will have to add one.") is more abrasive than necessary.

Chris2048• 3 months ago

Someone asking you to write a test for new code

per the response: "I'm not sure what kind of test would you like me to write for this change, as it's simply adding 4 quotes"

quectophoton• 3 months ago

I'm also not impressed with a carrot disclosure that looks like this. Running a python script to compromise a locally hosted instance? Bruh, you have physical hardware and host shell access. That python script could be doing anything including running as root.
Show us the exploit hitting a remote server.

Watch out, their script works on HN too, as a proof here's me logging in to YOUR computer's root account (a bit more redacted for obvious reasons):

    $ python3 ./poc/chain_alpha.py --target dangus > out.txt
    $ grep Backdoor out.txt |  sed -r 's@[^:]+$@ [REDACTED]@g'
    [+]   Backdoor admin created: [REDACTED]
    $ grep IP out.txt |  sed -r 's@[^:]+$@ [REDACTED]@g'
    [+]   IPv4 address for dangus: [REDACTED]
    $ grep 'debug2: shell' out.txt
    [+]   debug2: shell request accepted on channel 0
    $ tail -n12 out.txt 
    ================================================================
    [+] COMMAND EXECUTION CONFIRMED!
    ================================================================
    
    Server-side output (received via SSH, with `set -x`):

      + id -u
      0
      + id -g
      0
    
    ================================================================
    $ sha256 ./poc/chain_alpha.py
    c10d28a5ff74646683953874b035ca6ba56742db2f95198b54e561523e1880d7  ./poc/chain_alpha.py

unethical_ban2• 3 months ago

From a linked PR (related to this RCE?), from a maintainer who closed it:

Just thinking something not being used is not enough, even if it's a security sensitive topic

Linux kernel seems to disagree. This is a dangerously naive way to think of networked software in the AI age.

---

edit: I got hit with the "posting too fast" block again, so I'll reply to dangus here:

While a remote host would further prove the claim, the person clearly claims it is RCE, not just CE. It would be quite the pie in the face if the author wrote a python script to take in an IP address but modified system files on the backend to create a stunt.

dangus3• 3 months ago

It would definitely be a bit silly for the author to make a fake carrot disclosure, but I thought of it just because of how reading this article made me feel distrust toward the author. IDK, they just seem like kind of a jerk!

Now, I don't think the PRs with the Forgejo folks show a lot of warm collaborative energy on their side, either, but I can see how soft skills from the author would likely have taken their PRs a lot further in getting what they want.

But the author's whole attitude is that Forejo is such a mess and it's barely worth their time to try and clean it up. Nobody's twisting their arm to contribute to an open source project that they don't even like!

From the perspective of Forgejo maintainers, the author is just some random new contributor barging in and telling them to drop some legacy support that hasn't been discussed in detail yet. And of course, this new contributor hasn't actually followed the security policy to disclose it as a high severity issue to justify the change.

chillfox• 3 months ago

Don’t forget, repeatedly ignoring the requirements for including tests, and instead offering up a “have tested it locally, trust me” as a substitute.

conartist62• 3 months ago

Idunno, I think this model of disclosure feels more natural to me. The "coordinated" model can have the smack of extortion to it.

And yes, I very much want there to exist people whose specialty is finding security bugs. I wouldn't expect such a person to be a diehard contributor to any particular project. Their motivation isn't making one tool better, but keeping users safe. We need those people and the work they do badly!

JuniperMesos• 3 months ago

But the author's whole attitude is that Forejo is such a mess and it's barely worth their time to try and clean it up. Nobody's twisting their arm to contribute to an open source project that they don't even like!
From the perspective of Forgejo maintainers, the author is just some random new contributor barging in and telling them to drop some legacy support that hasn't been discussed in detail yet. And of course, this new contributor hasn't actually followed the security policy to disclose it as a high severity issue to justify the change.

It does affect my own willingness to use Forgejo, as a current non-user. It sounds like it has some security vulnerabilities that the maintainers aren't taking seriously, perhaps because they think the people who report those vulnerabilities are jerks. Are the Forgejo maintainers themselves sure that their software isn't going to get pwned in a way they don't have the right techniques to mitigate? I'd rather know that before I run it on my own infra.

000ooo000• 3 months ago

Hopefully someone a little more.. pragmatic gets eyes on that linked PR.

preinheimer2• 3 months ago

There’s an old cryptography story.

A cryptographer friend tells the story of an amateur who kept bothering him with the cipher he invented. The cryptographer would break the cipher, the amateur would make a change to “fix” it, and the cryptographer would break it again. This exchange went on a few times until the cryptographer became fed up. When the amateur visited him to hear what the cryptographer thought, the cryptographer put three envelopes face down on the table. “In each of these envelopes is an attack against your cipher. Take one and read it. Don’t come back until you’ve discovered the other two attacks.” The amateur was never heard from again.

https://www.schneier.com/crypto-gram/archives/1998/1015.html

neilv• 3 months ago

And if you are a dishonest cryptographer, you only need to find one attack to pull this off.

reverius42• 3 months ago

And who in the OP's post is the cryptographer, and who's the amateur, in this allegory?

preinheimer2• 3 months ago

I think the OP is presenting themselves as the cryptographer, and the authors behind Forgejo as the amateur. At this point they've only filled one envelope but believe there is many more to find, and are hoping that in the process of tracking down this one they'll find more.

mmsc• 3 months ago

https://codeberg.org/forgejo/governance/src/commit/5c07b3801...

Failure to comply with these rules will be criticized publicly, and we reserve the right to no longer coordinate with you or your project in the future.

lol

stock_toaster• 3 months ago

I could totally imagine this kind of thing being added due to AI-slop security report overload, like curl was experiencing[1].

[1] https://daniel.haxx.se/blog/2025/07/14/death-by-a-thousand-s...

jorams2• 3 months ago

This is a weird post to be honest. You've found a whole bunch of serious security issues, filed two PRs, one of which is adding some quotes because

Those aren't exploitable XSS, but it doesn't hurt to have a second layer of defense.

The other suggests breaking clients that aren't using the more secure version of an OAuth method because

I can't think of any OAuth client that would like to [use it]

That second one is a good idea, but the maintainer is also right to ask for some discussion before introducing a breaking change.

But crucially: neither of these are the kind of significant security issues you've found. Maybe lead with an actual bug?

arcfour• 3 months ago

Closing the PR without providing feedback beyond "needs further discussion" does not engender said further discussion.

PunchyHamster2• 3 months ago

PR isn't a place for discussion about what or how to implement change in the first place, that should be forum/mailing list/issues

and there is open issue for that discussion https://codeberg.org/forgejo/forgejo/issues/8634

henryteeare2• 3 months ago

The response was, "needs a discussion," as in a post on `https://codeberg.org/forgejo/discussions`, rather than directly creating a PR.

There also was feedback saying approximately that they've been burned by security changes in the recent past and don't want to run into similar issues without due consideration.

PunchyHamster2• 3 months ago

That second one is a good idea, but the maintainer is also right to ask for some discussion before introducing a breaking change.

The discussion seems to be already happening https://codeberg.org/forgejo/forgejo/issues/8634, author of the blog just did drive-by PR rather than looking at issue tracker

It's very much "I know better, do what I told you despise not thinking a second about any second order effects the change might cause" attitude that is so common with security people

henryteeare2• 3 months ago

I believe the discussion in #8634 is for a different change, but one of a similar nature.

unethical_ban2• 3 months ago

Yeah, ITOps and software teams are totally aware of the second order effects of their shitty software and compliance failures, security are always the wrong ones.

bogwog• 3 months ago

And attempting to publicly shame them into accepting a PR. Kinda reminds me of https://en.wikipedia.org/wiki/XZ_Utils_backdoor

gchamonlive2• 3 months ago

In the age of AI, carrot disclosure is potentially a full disclosure with extra steps. I'm no security expert, but with the context provided, the forgejo codebase and the outline of the redacted script, I think there is a good chance I could use codex to crunch through the vuln chain and reproduce the script.

nine_k• 3 months ago

Where's the vuln chain? Is it even obvious which APIs have been called?

gchamonlive2• 3 months ago

--- In this session we are going to explore the vulnerabilities documented in this carrot disclosure post at https://dustri.org/b/carrot-disclosure-forgejo.html and try to reproduce the script that explores the chain to gain admin access to forgego.

The post mentions just briefly what's been used to create the vuln chain: `SSRF in a lot of places, no CSP/Trusted-Types, a bit of ghetto templating in javascript, cryptographic malpractices, overlooks in the authentication mechanisms (OAuth2, OTP, sessions/access handling, post-compromission recovery, …), a bunch of low-hanging DoS, information leak all over the place, various TOCTOU, … All in all, it took me one evening after work to find a good amount of vulnerabilities (adding to the one I got from looking at gitea at some point in the past), and chain some of them to obtain a full-blown RCE`.

There is also the outline of the script call and the output we will use to base the script reproduction:

``` $ python3 ./chain_alpha.py --target http://127.0.0.1:3000 > out.txt $ grep Backdoor out.txt [+] Backdoor admin created: svc_ljeopgid / dukecepapsygiqks!A1 $ tail -n17 out.txt

================================================================ [+] COMMAND EXECUTION CONFIRMED! ================================================================

Server-side hook output (received via git push stderr):

  remote: ==========================================
  remote: FORGEJO RCE PoC - Command Execution Proof
  remote: ==========================================
  remote: hostname: chernabog
  remote: uid:      uid=1000(jvoisin) gid=1000(jvoisin) groups=1000(jvoisin),10(wheel) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
  remote: date:     Tue Apr 28 19:16:59 UTC 2026
  remote: proof:    chernabog
  remote: ==========================================

================================================================ $ sha256 ./chain_alpha.py c10d28a5ff74646683953874b035ca6ba56742db2f95198b54e561523e1880d7 ./poc/chain_alpha.py jvoisin@chernabog 11:35 ~/Documents/exploits/forgejo tree . ├── chain_alpha.py ├── chain_beta.py ├── chain_gamma.py ├── dos │ ├── cpuburn_authenticated.py │ ├── cpu_dos.py │ ├── dbburn.py │ ├── dfburn.py │ ├── exhaust.py │ ├── gburn.py │ ├── grpstarve.py │ ├── rstarve.py │ ├── starve.py │ └── storage.py ├── f9_repo_settings.py ├── get_version.py ├── leak_secrets.py ├── leak_token.py ├── merge.py └── NOTES.md

2 directories, 19 files $ ```

Our working directory already contains the source for forgego.

I am no security expert so we will need to approach this in four stages:

First I need you to guide me through each of the vuln concepts exposed in the article. In this step I am going to read through them and understand each of them.

I am also not familiar with forgego codebase, so in the second step I need you to guide me through the code, as we explore and understand the architecture and implementation of this git platform.

In the third stage we are going to validate my understanding of the first stage by linking each of the concept with the actual codebase.

Finally, in the fourth stage we are most likely prepared to tackle reproducing the vuln chain exploit.

Create one work item for each step. We are going to go through each of them in separate sessions.

flumpcakes2• 3 months ago

Did the author actually disclose this RCE or just open random PRs and claim there's an issue?

It doesn't appear like the author is acting in good faith, instead grandstanding in public because they feel superior.

apublicfrog2• 3 months ago

The author quite clearly outlines their reasoning for this in the article:

Carrot Disclosure, dangling a metaphorical carrot in front of the vendor to incentivise change. The main idea is to only publish the (redacted) output of the exploit for a critical vulnerability, to showcase that the software is exploitable. Now the vendor has two choices: either perform a holistic audit of its software, fixing as many issues as possible in the hope of fixing the showcased vulnerability; or losing users who might not be happy running a known-vulnerable software. Users of this disclosure model are of course called Bugs Bunnies.

flumpcakes2• 3 months ago

Seems like grandstanding bad faith to me. They didn't even bother to follow the established disclosure policy for this project because the author feels this quality of the code is so crap, so instead does this...

isodev• 3 months ago

This entire post reads as rage bait. They’re mad because Forgejo has … a process? And what are these vulnerabilities, concretely?

But given the sorry state of the codebase

I honesty want a refund on the 10 minutes I wasted reading this.

yunnpp• 3 months ago

I cracked at the last statement, lol. Really encapsulates my overall feeling reading some HN submissions lately.

throwaway38294• 3 months ago

I run a forgejo instance at home but wouldn't dream of opening it up to the public. Works great, and fast on lan, but imo keep it there

kasdklasmdads• 3 months ago

Imagine if every open source contributor behaved like that.

"I found performance problems in your software, but I won't disclose them until you fix them."

"I'm a designer, but I won't disclose my improvement to your project until you adjust all the CSS bugs in your project."

If that person is skilled with finding security bugs, then that could be their contribution to that open-source project, like any other contribution.

gbraad• 3 months ago

This is so wrong. Because he didn't like a PR removing a feature, and they haven't yet merged another PR that was opened yesterday?!?

pabs33• 3 months ago

I note that the code that pull request 12283 is changing builds HTML via string concatenation/templates, which is a widespread source of XSS problems. Maybe it is time to for browsers and JavaScript runtimes/libraries to deprecate string based HTML building and require DOM based instead. The former is unsafe by design and the latter is a safe-by-construction approach.

Getting HTML building right is a pretty basic building block of web apps, Forgejo can't have great security practices if they aren't doing that. So I can easily imagine the OP is correct in their assessment of Forgejo code security.

jeremiahlee• 3 months ago

The author sent 5 more pull requests fixing (tragically) fundamental security flaws. https://codeberg.org/forgejo/forgejo/pulls?q=&type=all&sort=...

bmitch3020• 3 months ago

Forgejo has responded:

The author of the recent 'Carrot disclosure' blog post has contacted the Forgejo Security team with their findings. The issues raised concern defence-in-depth improvements and denial-of-service risks. There is no known RCE exploit possible without internal server credentials.
We believe these findings can be addressed publicly. The security team will open issues where approaches to implement new defensive measurements will be discussed, we believe there's no single answer and as such appreciate the opinion of other Forgejo contributors on this matter.

https://floss.social/@forgejo/116494295922963052

throwa356262• 3 months ago

Okay, this sounds familiar.

If you run Claude Opus 4.6 at max settings on forgejo repo, it will give you a bunch of RCE's ... that need prior knowledge of the server internal token :) You have to tell the stupid LLM that these attacks doesn’t make sense.

The author seem to be a experienced security researcher. I am surprised he didn't catch this.

weiliddat• 3 months ago

Let's go one step further and think about why OSS maintainers generally approach security vulnerabilities the way they do (even pre-AI), and why some people has a significant negative reaction to this type of bug/security/issue reporting approach.

What happens if they treat every single report with the same effort and seriousness regardless of how it is reported? What happens if they dedicate too much effort in wild goose hunts while disregarding the more mundane/concrete security and maintenance work? How would an attacker take advantage of this process?

If you work in software, maybe you've encountered this yourself, in orgs where they don't have good processes around reporting bugs/issues. You essentially get DoSed by noise. You get tons of issues from customers (or internal stakeholders representing them), some barely describing stuff like "hey X can access Y, don't think they should" without any context (or even refusing to provide further information even after you ask), forcing you/CS to prune down all possible paths based on audit logs and their permission settings and so on.

Customers (in this case I'd say OSS users are customers too) can say "yeah this is the responsibility of the maintainers/vendors, why should I even care to report things a certain way, be glad I even told you at all" but IME this social posture is terrible for both parties. Even in commercial relationships, the best customers I've had were ones that reported issues that were concrete and reproducible. The chances I can fix it almost immediately goes up in orders of magnitude. The customer gets what they want and my job is simpler.

Even the core claim of the article, "this is a systemic issue", isn't fixed by a carrot disclosure. They don't imply an organizational/structural issue, merely a legacy one (inheriting stuff from gitea/gogs). What do you gain more by putting social-political pressure on an OSS project, if it's not a social-political problem?

The post reads more like an emotional response (frustration) rather than a productive one.

Carrot Disclosure: Forgejo

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