CVE-2026-4691 - Vulnerability Analysis
CriticalCVSS: 9.8Last Updated: March 24, 2026
Firefox - Use After Free
Published: March 24, 2026Updated: March 24, 2026Remote Exploitable
Overview
Firefox < 149, Firefox ESR < 115.34, and Firefox ESR < 140.9 contain a use-after-free vulnerability caused by flaws in the CSS Parsing and Computation component, letting attackers cause memory corruption, exploit requires crafted content.
Severity & Score
Severity: Critical
CVSS Score: 9.8
Impact
Attackers can cause memory corruption leading to potential code execution or application crash.
Mitigation
Update to Firefox 149, Firefox ESR 115.34, Firefox ESR 140.9 or later.
References
- 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/
- https://bugzilla.mozilla.org/show_bug.cgi?id=2017512
Related Resources
Details
- CVE ID
- CVE-2026-4691
- Severity
- Critical
- CVSS Score
- 9.8
- Type
- use_after_free
- Status
- modified
CWE
- CWE-416
CVSS Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H