Node2Shell Hits Python Too: Check Your Brotli and brotlicffi Versions

An analysis published on October 23 describes how CVE-2026-111497 affects the Brotli and brotlicffi packages for Python. The GitHub advisory database entry was also updated that day. The vulnerability itself was already known.

What has been confirmed

The flaw is in the shared Brotli decoding library. Updating Node.js does not fix the vulnerable copies that Python applications use.

The GitHub advisory lists two vulnerable packages: Brotli from version 1.0.3 up to but not including 1.2.1, and brotlicffi from version 1.0.3 up to but not including 1.2.1.0. The fixed releases are 1.2.1 and 1.2.1.0. Patched versions are also available on the older 1.0.10 and 1.1.1 branches of the Brotli library itself.

How the threat arises

An HTTP client may decompress Brotli responses automatically if the right package is installed. This means attacker-controlled data can reach the decoder through a response from an external server. A second path is compressed requests, if the application or a layer in front of it decompresses them.

The vulnerability can cause memory corruption. The code execution demo in Node.js does not prove that a Python application has been successfully attacked.

What to do now

• Check the versions of both packages in every deployed environment.
• Install Brotli 1.2.1 and brotlicffi 1.2.1.0 or later.
• Update your dependency lock files, rebuild container images and redeploy services.
• If you don’t need Brotli decoding, consider removing the packages after confirming your application still works without them.

Removing br from the Accept-Encoding header does not by itself protect you from a malicious server response.

SecurHUB commentary

A dependency review should cover what is actually running in production. Security audits help identify which services use the vulnerable component and need to be redeployed.

Sources: GitHub security advisory, Aikido analysis