Critical Brotli Decoder Flaw 'Node2Shell' Reaches Node.js, Bun and Python
CVE-2026-111497, an out-of-bounds write in the Brotli decoder with a CVSS of 9.2, affects multiple runtimes; patches shipped 21 October.
A critical vulnerability tracked as CVE-2026-111497, an out-of-bounds write in Google's Brotli decoder with a CVSS 4.0 score of 9.2 from Google, has been confirmed to affect Node.js 22/24/26, Bun up to 1.4.3, and the Python packages brotli and brotlicffi. Malicious compressed data can overwrite memory buffers, leading to crashes, memory disclosure or remote code execution. Imperva researchers demonstrated working code execution on unpatched Node.js 24.22.0. Fixed versions include Brotli 1.0.10/1.1.1/1.2.1, Node.js 22.23.4/24.22.1/26.12.1, Bun 1.4.4 and Python brotli/brotlicffi 1.2.1 or later.
The flaw was found by OpenAI's Codex Security team during agentic red-teaming and disclosed on 21 October; the underlying fix had existed in the Brotli source since February but was never released upstream for eight months. Because each product embeds its own copy of the decoder, every downstream project must patch separately. CISA assessed on 23 October that there is no known in-the-wild exploitation yet, but technical PoCs are public.