All vulnerabilities
GHSA-9v8h-qqgm-4m35

Brotli: Out-of-bounds write in the Brotli decoder ("Node2Shell") also affects the PyPI Brotli package

brotlipipLibraries & packages
Open in ThreatlineRecord JSON
CVSS
9.2Critical
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)No scoreNo FIRST EPSS score in this snapshot yet
Fixed in1.2.1Also 1.2.1.0GitHub
Published22 Oct 2026Updated 23 Oct 2026GitHub

What fixes it

  • 1.2.1brotli, pipGitHub
  • 1.2.1.0brotlicffi, pipGitHub
  • 1.2.1brotli, PyPIOSVpip install "brotli>=1.2.1"
  • 1.2.1.0brotlicffi, PyPIOSVpip install "brotlicffi>=1.2.1.0"

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Description

A buffer overflow vulnerability in the Brotli decoder (c/dec/decode.c) in Google Brotli versions 1.0.3 through 1.2.0 on all platforms allows a remote unauthenticated attacker to corrupt adjacent decoder state memory, disclose sensitive memory contents, cause a denial of service, or potentially execute arbitrary code using a crafted Brotli-compressed stream.

Users need to update any Brotli libraries or binaries between 1.0.3 through 1.2.0 to the latest available version: 1.0.10 or 1.1.1 or 1.2.1.

Text from GitHub Advisory Database

Affected versions 18

  • brotli, pip>= 1.0.3, < 1.2.1GitHub
  • brotlicffi, pip>= 1.0.3, < 1.2.1.0GitHub
  • brotli, PyPIfrom 1.0.3, fixed in 1.2.1OSV
  • brotli, PyPI1.0.4OSV
  • brotli, PyPI1.0.6OSV
  • brotli, PyPI1.0.7OSV
  • brotli, PyPI1.0.8OSV
  • brotli, PyPI1.0.9OSV
  • brotli, PyPI1.1.0OSV
  • brotli, PyPI1.2.0OSV
  • brotlicffi, PyPIfrom 1.0.3, fixed in 1.2.1.0OSV
  • brotlicffi, PyPI1.0.9.0OSV
  • brotlicffi, PyPI1.0.9.1OSV
  • brotlicffi, PyPI1.0.9.2OSV
  • brotlicffi, PyPI1.1.0.0OSV
  • brotlicffi, PyPI1.2.0.0OSV
  • brotlicffi, PyPI1.2.0.1OSV
  • brotlicffi, PyPI1.2.0.2OSV

References 17