On top of that, the brotli library saw no releases for almost a full year, with the fix for this vulnerability being committed back in February. Google builds from main for all their projects, so were unaffected, but open source releases are a complete afterthought. Over 100 commits with miscellaneous fixes left languishing until a security incident forces a release.

For clients? Sure, that's a bigger risk. Patch them. But bad guys aren't attacking your clients unless the clients connect to them. Don't stay up late to fix this.

(And yes, .NET is included here, because Microsoft's Brotli module is a binding for Google's vulnerable reference implementation.)

The python package has already been updated to 1.2.1. https://pypi.org/project/brotli/1.2.1/

And this commit contained a refactoring from BROTLI_BOOL to BrotliDecoderErrorCode so the situation was that probably one of the error conditions previously simply returned false but needed more detail about what went wrong to continue safely.

Well okay this change from `if (prev_ix < cur_ix)` to `if (prev_ix < cur_ix && cached_backward <= max_backward)` is also suspicious and could be an related or unrelated hardening fix.

Very easy to reproduce the with a single httpx.get(URL) in Python, but I couldn’t figure out an ASLR bypass from that context. Crashing is easy and I (with LLM assistance) can get some read/write primitives, but no chain into getting a function pointer where I needed it. Probably needs heap manipulation, but I lost interest at that point.

Really hoping we see an actual RCE PoC. Also, the open weight models can easily provide a "regression test" that would shoo away most crawlers.

A significant blast radius

Is it really so hard to write a 2 sentence tweet that you need an AI to do it for you?

https://x.com/AikidoSecurity/status/2113759110625906950

and this is the actual CVE report, which doesn't say much: https://www.cve.org/CVERecord?id=CVE-2026-111497

[1] When more than half of the "standard" https://www.rfc-editor.org/info/rfc7932/#page-44 is an opaque binary blob, they're really not encouraging independent implementations.

Edit: the votes really show what an echochamber for Big G this place has become. FUCK YOU, GOOGLE!

This is not a server-side issue (unless for some weird reason you're using Brotli decoding in your http request processing), it's client-side.

Thank you Paul for the write-up (https://opensourcemalware.com/blog/node2shell-affects-python)