CVE-2026-0878

firefox: thunderbird: Sandbox escape due to incorrect boundary conditions in the Graphics: CanvasWebGL component

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Severity

Important

Red Hat Product Security

7.5

CVSS 3.1

Review impact separately from score.

Published · January 13, 2026

Updated · October 16, 2026

Description

A flaw was found in Firefox and Thunderbird. The Mozilla Foundation's Security Advisory describes the following issue: Sandbox escape due to incorrect boundary conditions in the Graphics: CanvasWebGL component

Statement

Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory.

CVSS score applicability

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.

CVSS / CWE

CVSS 3.1 · 7.5
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

CWE-119 · Improper Restriction of Operations within the Bounds of a Memory Buffer