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Python Library brotlicffi 1.0.3 < 1.2.1.0 Out-of-Bounds Write (Brotli2Shell)

critical Nessus Plugin ID 372407

Synopsis

A Python library installed on the remote host is affected by an out-of-bounds write vulnerability.

Description

The detected version of the brotlicffi Python package is 1.0.3 or later but prior to 1.2.1.0. It is, therefore, affected by an out-of-bounds write vulnerability in the bundled Brotli decoder:

 - 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. (CVE-2026-111497)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Upgrade to brotlicffi version 1.2.1.0 or later.

See Also

https://github.com/advisories/GHSA-9v8h-qqgm-4m35

https://github.com/google/brotli/releases/tag/v1.2.1

Plugin Details

Severity: Critical

ID: 372407

File Name: python_brotlicffi_1_2_1_0.nasl

Version: 1.1

Type: Local

Agent: windows, macosx, unix

Family: Misc.

Published: 10/27/2026

Updated: 10/27/2026

Configuration: Enable thorough checks (optional)

Supported Sensors: Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: High

Score: 7.9

Percentile: 99.33

CVSS v2

Risk Factor: High

Base Score: 7.5

Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P

CVSS Score Source: CVE-2026-111497

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v4

Risk Factor: Critical

Base Score: 9.2

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

Vulnerability Information

CPE: cpe:/a:google:brotli

Patch Publication Date: 10/22/2026

Vulnerability Publication Date: 10/21/2026

Reference Information

CVE: CVE-2026-111497