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Vulnerabilities

Vulnerability · GHSA-9v8h-qqgm-4m35

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

Published Oct 22, 2026 · catalog updated Oct 23, 2026 · Brotli: Out-of-bounds write in

Last checked Oct 23, 2026, 13 days ago.

Open the advisory

Exploitation likelihood is not on this record for GHSA-9v8h-qqgm-4m35. A missing EPSS score is not a low risk. Compare Brotli: Out-of-bounds write in with the linked advisory before you change production.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Brotli: Out-of-bounds write in).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
  • EPSS is missing. A missing score is not a low risk.
Severity
Critical—
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
Awaiting synchronization with FIRST
Remediation
Advisory link
Affected products
PyPI brotli · PyPI brotlicffi

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • PyPI brotli1.0.3 → 1.2.1
  • PyPI brotlicffi1.0.3 → 1.2.1.0

How to fix GHSA-9v8h-qqgm-4m35

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

Exploitation likelihood is not on this record for GHSA-9v8h-qqgm-4m35. A missing EPSS score is not a low risk. Compare Brotli: Out-of-bounds write in with the linked advisory before you change production.

Which versions are affected?

Compare what you have installed with 1.0.3 → 1.2.1, 1.0.3 → 1.2.1.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-252: Unchecked Return Value. EPSS is not on this record yet. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 22, 2026 · PyPA Advisory Database

    Detected

    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 librarie

  2. Oct 23, 2026 · PyPA Advisory Database

    Fix available

    brotli fixed in 1.2.1; brotlicffi fixed in 1.2.1.0

  3. Oct 23, 2026 · PyPA Advisory Database

    Fix available

    brotli fixed in 1.2.1

  4. Oct 23, 2026 · PyPA Advisory Database

    Fix available

    brotlicffi fixed in 1.2.1.0

  5. Oct 23, 2026 · PyPA Advisory Database

    Updated

    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 librarie

Sources

References

Freshness

Last verified in this catalog Oct 23, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • CIRCL Vulnerability LookupOct 23, 2026
  • PyPA Advisory DatabaseOct 23, 2026