CVE-2026-4691

Description

Use-after-free in the CSS Parsing and Computation component. This vulnerability was fixed in Firefox 149, Firefox ESR 115.34, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.

Affected Platforms

Weakness Type

CWE-416, CWE-416, CWE-825

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=2017512
• https://www.mozilla.org/security/advisories/mfsa2026-20/
• https://www.mozilla.org/security/advisories/mfsa2026-21/
• https://www.mozilla.org/security/advisories/mfsa2026-22/
• https://www.mozilla.org/security/advisories/mfsa2026-23/
• https://www.mozilla.org/security/advisories/mfsa2026-24/