Aikido Security said Friday that the Brotli decoder flaw behind Node.js Node2Shell, tracked as CVE-2026-111497, also affects two PyPI packages, Brotli and brotlicffi, which compile the same decoder Node.js bundles¹.

The firm said Brotli 1.2.0 and earlier and brotlicffi 1.2.0.x are affected, with fixes in Brotli 1.2.1 and brotlicffi 1.2.1.0¹. It cited 82.8 million monthly downloads for Brotli on PyPI and said the CVE record pairs CWE-252 with CWE-787 (out-of-bounds write) and lists a CVSS 4.0 score of 9.2¹.

Aikido said an app can be exposed without importing Brotli in its own code: HTTP clients such as urllib3 (and therefore requests), httpx with a brotli extra, and aiohttp can load the packages when they are installed¹. It said an attacker can reach the decoder through a malicious Brotli response to an outbound request or a request body sent with Content-Encoding: br¹.

Node.js released patched versions around Oct. 21, Aikido said, and Brotli 1.2.1 appeared on PyPI on Oct. 22, with brotlicffi 1.2.1.0 on Oct. 23¹. The firm said as of Oct. 23, pip-audit, Dependabot and Safety may not flag the PyPI packages because advisory databases had not mapped the CVE to them¹.

Where an upgrade is not yet possible, Aikido recommended uninstalling Brotli and brotlicffi so clients fall back to gzip and deflate, and said stripping br from Accept-Encoding is weaker for outbound traffic because a server can still send a Brotli body¹. It said OpenSourceMalware.com published related research on the Python packages on Oct. 23 and that OSM did not pursue memory corruption or code execution in the Python extension¹.

WhatsNewPaper has not independently verified the CVE scoring, download counts or whether scanners now map the packages¹.

Sources

1. aikido.devPython packages are also vulnerable to the Node2Shell Brotli flaw (CVE-2026-111497)Oct 22, 8:00 PM

Read the original at aikido.dev ↗