CVE-2026-111497: Out-of-Bounds Write in Google Brotli Decoder

Analysis on rafaelpfister.ch

Article · October 26, 2026 CVE-2026-111497: Flaw in Brotli decoder affects Node.js, Bun, Python, .NET, and Envoy—what you need to update now A flaw in Google's Brotli decoder (versions 1.0.3 through 1.2.0) allows an out-of-bounds write, potentially leading to code execution, using crafted data (CVE-2026-111497, CVSS 9.2). Any software that decompresses Brotli data from untrusted sources is affected: Node.js, Bun, Python with Brotli/brotlicffi, .NET, Envoy, and curl. Updates are available.

Vendor 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.

Reference data

Vendor

Google

Affected products

Brotli

CVSS 4.0

9.2 (CRITICAL)

Vector

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

Weakness type

CWE-787: Out-of-bounds Write

Published

October 22, 2026

In KEV catalog since

October 27, 2026

US federal deadline

November 10, 2026

Official sources

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CVE-2026-111497 Out-of-Bounds Write in Google Brotli Decoder

Analysis on rafaelpfister.ch

Vendor description

Reference data

Official sources

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