Package vulnerability, severity critical
Brotli: Out-of-bounds write in the Brotli decoder ("Node2Shell") also affects the PyPI Brotli package
Published , updated
Brotli: Out-of-bounds write in the Brotli decoder ("Node2Shell") also affects the PyPI Brotli package. Actively exploited (CISA KEV). Source: GHSA-9v8h-qqgm-4m35 (BIT-brotli-2026-111497, BIT-dotnet-2026-111497, BIT-dotnet-sdk-2026-111497).
What's affected
- brotli (pypi)>=1.0.3 <1.2.1
- brotlicffi (pypi)>=1.0.3 <1.2.1.0
What to do
- Upgrade brotli to 1.2.1 or later.
- Upgrade brotlicffi to 1.2.1.0 or later.
Check whether you were affected
Pharon tells teams automatically when this affects something they run. To check a machine, run this in Claude Code with the Pharon plugin, in the repository that uses it:
/pharon:check-incident ghsa-9v8h-qqgm-4m35References
- https://osv.dev/vulnerability/GHSA-9v8h-qqgm-4m35
- https://nvd.nist.gov/vuln/detail/CVE-2026-111497
- https://github.com/dotnet/announcements/issues/494
- https://github.com/google/brotli/commit/da9806362874b9bd4b552a3af360b5d6347beb12
- https://github.com/google/brotli/commit/b418fa81c48262a86a95332b0bc6d62c30aa78b6
- https://github.com/google/brotli/commit/50a9b70a4d5e1443fc40927952276b68fffa83a0
- https://github.com/google/brotli/commit/0ed4268a4401abcb4472096340477cf4af7d1a2b
- https://github.com/pypa/advisory-database/tree/main/vulns/brotlicffi/PYSEC-2026-4323.yaml
- https://lists.debian.org/debian-lts-announce/2026/10/msg00049.html
- https://nodejs.org/en/blog/vulnerability/october-2026-security-releases
Notice ghsa-9v8h-qqgm-4m35, signed with key feed-prod-2026-10 (Ed25519). The Pharon CLI verifies the signature before using a notice.