Python Library Brotli 1.0.3 < 1.0.10 / 1.1.x < 1.1.1 / 1.2.x < 1.2.1 Out-of-Bounds Write (Brotli2Shell)

critical Nessus Plugin ID 372406

Synopsis

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

Description

The detected version of the Brotli Python package is 1.0.3 or later but prior to 1.0.10, or 1.1.x prior to 1.1.1, or 1.2.x prior to 1.2.1. 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 Brotli version 1.2.1 or later.

Plugin Details

Severity: Critical

ID: 372406

File Name: python_brotli_1_2_1.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: 10/21/2026

Vulnerability Publication Date: 10/21/2026

Reference Information

CVE: CVE-2026-111497

Detections

Analytics