CVE-2025-10527: Sandbox escape due to use-after-free in the Graphics: Canvas2D component

Severity: high (CVSS 7.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-09-16 · updated 2026-10-23
Weakness: CWE-416

Description

Sandbox escape due to use-after-free in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 143, Firefox ESR 140.3, Thunderbird 143, and Thunderbird 140.3.

Affected products

Mozilla Firefox: before 140.3.0; through 143.0 — fixed in 140.3.0
Mozilla Thunderbird: before 140.3.0; from 141.0 before 143.0 — fixed in 140.3.0, 143.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 140.3.0; Mozilla Thunderbird 140.3.0, 143.0. Check the vendor advisory for mitigations.

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1984825
https://www.mozilla.org/security/advisories/mfsa2025-73/
https://www.mozilla.org/security/advisories/mfsa2025-75/
https://www.mozilla.org/security/advisories/mfsa2025-77/
https://www.mozilla.org/security/advisories/mfsa2025-78/
https://lists.debian.org/debian-lts-announce/2025/09/msg00020.html
https://lists.debian.org/debian-lts-announce/2025/09/msg00026.html

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