Brotli flaw allows unauthenticated remote code execution in Node.js, Bun, Envoy and curl

OpenAI says its high-compute red-teaming exercise also found a vulnerability in Brotli, the compression library built into Node.js, Bun, Envoy and many other programs. It is tracked as CVE-2026-111497.

What OpenAI says:

• The flaw allows unauthenticated remote code execution through malicious compressed data. An unpatched server that accepts compressed input could be taken over by a malicious client, and an unpatched client that accepts compressed input (for example curl --compressed) could be taken over by a malicious server.
• The root cause was fixed in the Brotli source in February, but nobody knew it was a security vulnerability and no release followed. Because Brotli is bundled into other software, every project that includes it has to take the update, and then its users do too.
• OpenAI disclosed the flaw to Brotli and to downstream projects such as Node.js. It says they have released or are releasing security updates, and that Brotli cut new releases and published the CVE. Details and mitigations are on patchtheplanet.org/brotli.

What Aikido Security says: the flaw, first seen affecting Node.js and Python, reaches many libraries and applications that use HTTP, and it calls it "HTTP2Shell". Fixes are not yet available for every affected service; it advises looking for Brotli 1.2.1 dependency upgrades as they appear. Aikido lists patches so far for libbrotli, Python, C++, Node.js and Envoy (Envoy's own advisory is GHSA-3wvj-j6qm-62mr) and says more are coming.