OpenAI red team finds critical Brotli RCE (CVE-2026-11149) hitting Node.js, Bun, Envoy
moyix · x · 2026-10-24
During a red-teaming exercise, OpenAI discovered an unauthenticated remote code execution vulnerability in Brotli, a widely deployed compression library (CVE-2026-11149, high), affecting Node.js 22.x/24.x/26.x, Bun, Envoy and more.
- Root cause: an invalid block switch is reported as a temporary need for more input instead of a format error, so the streaming decoder keeps appending bytes to an 8-byte internal buffer — an out-of-bounds write that can crash processes, leak memory, or enable RCE.
- Attack surface: no account needed — an unpatched server accepting compressed input can be taken over by a malicious client, and clients like curl --compressed by a malicious server.
- Credits: found via OpenAI's large-scale infrastructure code scanning by Codex Security's Khai Tran and Sylvie Mayer; fixed by mcollina and aduh95.
- Advice: update anything using Brotli ASAP.
Related event: OpenAI Red Team Uncovers Unauthenticated RCE Flaw in Brotli(2 posts)→
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