OpenAI red team uncovers unauthenticated RCE in Brotli; patched Node.js releases out

During an OpenAI red team exercise, its Codex Security team found an unauthenticated remote code execution vulnerability in the widely deployed compression library Brotli (rated high; most posts cite CVE-2026-111497). Greg Brockman said the team is coordinating disclosure and fixes; patched Node.js releases are already out, and services should upgrade promptly.

Confirmed

• The flaw is an unauthenticated RCE: an attacker only needs to send malicious compressed data to execute code on unpatched servers or clients; per @seanwbren, unpatched servers could be hijacked, and client-side exploitation (e.g., curl downloads) was also raised
• Affected software includes Node.js, Bun, Envoy, cURL and others that bundle Brotli; Node.js 22.x/24.x/26.x are all affected
• Researcher julianor reproduced the memory-corruption bug with a simple Node.js + Express app; key finding: patched and unpatched versions decompress differently, allowing attackers to remotely fingerprint unpatched servers
• Fixed releases are available: Node.js 22.23.4, 24.22.1 and 26.12.1; @fekdaoui reports Codex Security used AI to patch 104 containers in an hour

Unconfirmed

• The CVE ID differs across posts (most say CVE-2026-111497; one post says CVE-2026-11149); the exact ID awaits official clarification

Why it matters

• Brotli is a compression format used broadly by browsers and servers and bundled in many downstream products, giving the flaw a huge attack surface; it requires no authentication, so any service accepting compressed input is exposed
• The divergent decompression output between patched and unpatched versions enables pre-exploitation fingerprinting, complicating defense; affected services should upgrade to fixed versions as soon as possible

2026-10-23 ~ 2026-10-24 · 6 related posts

Full story(3 episodes)→

• Episode 1: Node.js Ships Security Updates Across 22/24/26 Lines Fixing Brotli RCE(2026-10-21, 10 posts)
• Episode 2: OpenAI red team uncovers unauthenticated RCE in Brotli; patched Node.js releases out(2026-10-23, 6 posts)
• Episode 3: Brotli Decoder Out-of-Bounds Write Flaw Hits Python Ecosystem(2026-10-24, 2 posts)

• [source] Brotli memory corruption bug CVE-2026-111497 reproduced with a simple Node.js app — evilsocket · 2026-10-23
• OpenAI red team finds critical Brotli RCE (CVE-2026-11149) hitting Node.js, Bun, Envoy — moyix · 2026-10-24
• [source] OpenAI red team finds unauthenticated RCE in widely deployed Brotli compression library — gdb · 2026-10-24
• OpenAI discloses critical Brotli flaw enabling unauthenticated system takeover in Node.js, Bun, Envoy — seanwbren · 2026-10-24
• [source] OpenAI Codex Security finds Brotli bug; agent patches 104 containers in 1h 8m — fekdaoui · 2026-10-24

1 near-duplicate retellings: charliermarsh