Connect your agent
AdvisoriesCriticalCheck your lockfilePluginHow it worksPricing Connect your agent

Advisory record · GHSA-9v8h-qqgm-4m35

Excessive memory allocation when decompressing crafted streams in github.com/andybalholm/brotli

CVSS 9.2 CriticalCriticalIn CISA KEVEPSS 0.83 · 99th percentile

Critical, because:

  • In CISA’s KEV catalogue since 27 Oct 2026: it is known to be exploited.
  • CVSS score 9.2: 9.0 or more.
  • CVSS score 9.2 (7.0 or more) and EPSS 0.83 (0.1 or more): a high score and a real chance of exploitation in the next 30 days.

How we decide what’s critical

Published by the GitHub Advisory Database at 5 Nov 2026, 22:55 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
github.com/andybalholm/brotliGo<1.2.71.2.7
Identifiers
GHSA-9v8h-qqgm-4m35 · BIT-brotli-2026-111497 · BIT-dotnet-2026-111497 · BIT-dotnet-sdk-2026-111497 · BIT-node-2026-111497 · BIT-node-min-2026-111497 · BIT-powershell-2026-111497 · CVE-2026-111497 · GHSA-c9gr-gmg4-2vqv · GO-2026-6888 · PYSEC-2026-4322 · PYSEC-2026-4323
Weakness (CWE)
CWE-252 · CWE-787
Tags
Published
5 Nov 2026
Updated
5 Nov 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

The PyPI packages brotli (1.0.3 up to but not including 1.2.1) and brotlicffi (1.0.3 up to but not including 1.2.1.0) have an out-of-bounds write in the Brotli decoder. A remote, unauthenticated attacker can use a crafted Brotli-compressed stream to corrupt adjacent memory, disclose memory contents, cause a denial of service, or possibly execute arbitrary code. Upgrade to brotli 1.2.1 or brotlicffi 1.2.1.0.

Written 31 Oct 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
9.2 Critical 4.0 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N CNA (Google)
  • CISA KEV Listed since 27 Oct 2026: known to be exploited.
  • EPSS 0.83, the 99th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 22 Oct 2026, 13:35 UTC Confirmed by the CVE List
  2. 22 Oct 2026, 14:17 UTC Confirmed by NVD
  3. 22 Oct 2026, 15:32 UTC Confirmed by GitHub Advisory Database
  4. 31 Oct 2026, 14:07 UTC First seen by agentprime
  5. 31 Oct 2026, 14:07 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.