CVE-2026-4691 - Vulnerability Analysis

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

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://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/

Related Resources

• Vulnerability Intelligence Dashboard
• Credential Scanner