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CVE-2026-111497

Out-of-Bounds Write in Google Brotli Decoder

  • Critical 9.2
  • Exploited: added to CISA KEV 27 Oct 2026

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.

Key facts

Published
22 Oct 2026
Last changed
10 Nov 2026
Assigned by
Google
KEV added
27 Oct 2026
KEV fix due
10 Nov 2026
EPSS
82.641% likely to be exploited in the next 30 days, higher than 99.673% of CVEs (scores for 15 Nov 2026)
SSVC (CISA)
Exploitation: active; Automatable: no; Technical impact: total

Severity scores

Each score is shown as its source gave it. They are not averaged or merged.

  • 9.2CVSS 4.0, Criticalfrom the CNA (Google)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

What to do

  • 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.CNA solution statement
  • Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.CISA KEV required action

Historical context and remediation

This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.

CAPEC-100 Overflow Buffers (CNA impact statement)

Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.

Read the original CVE record.

Affected products

VendorProductVersions
GoogleBrotli
  • Default status: unaffected
  • 1.0.3 up to but excluding 1.0.10 (affected)
  • 1.1.0 up to but excluding 1.1.1 (affected)
  • 1.2.0 up to but excluding 1.2.1 (affected)

Timeline

  1. 22 Oct 2026 Published
  2. 27 Oct 2026 Added to the CISA KEV catalogue

Weakness

Related coverage

References