# OpenAI finds unauthenticated remote code execution flaw in Brotli compression library

> Original title: we've found and have been working on disclosure for a remote code execution in a widely-deployed compression library.

- Source: Greg Brockman
- Published: 2026-10-23T23:25:18.000Z
- Bad Influence: https://badinfluence.news/items/pedinwekml8zjpja0gqn3nqcd
- Original: https://x.com/gdb/status/2113773790207283353

## Summary

Greg Brockman says the team found and is disclosing a remote code execution vulnerability in Brotli, a widely used compression library. OpenAI's quoted post says an attacker could take over affected servers or clients by sending malicious compressed data, without an account. The root cause was fixed in February, but Brotli released a new version and a CVE only after the security impact became known, and downstream projects such as Node.js are shipping updates.

## Post

we've found and have been working on disclosure for a remote code execution in a widely-deployed compression library.

it's both an impactful issue and an example that shows how complicated it can be to coordinate patching, since it's integrated into a lot of downstream software:

## Quoted post @OpenAI

> During this red-teaming exercise, we also found a vulnerability that allows for unauthenticated remote code execution in Brotli, a widely-deployed compression library included in many pieces of software such as Node.js, Bun, and Envoy.
> 
> The flaw could let an attacker run their own code on affected systems by sending or replying with malicious compressed data, without any need to create a user account. That is, an unpatched server that accepts compressed input could be taken over by a malicious client, and an unpatched client that accepts compressed input (such as “curl --compressed”) could be taken over by a malicious server.
> 
> This root cause issue was actually fixed in the Brotli source code in February, but it wasn’t known at the time that it gave rise to a security vulnerability and there was no more recent release of Brotli. Since Brotli is built into other software, any software which includes this library needs to take the update too, followed by the users of that software. We disclosed the vulnerability to Brotli and other downstream projects such as Node.js, which released or are currently releasing security updates, and Brotli cut new release versions and published a CVE.
> 
> More details on the patch and mitigations below:
> https://patchtheplanet.org/brotli

https://x.com/OpenAI/status/2113766354386084338