Vulnerability in Mozilla Firefox

CVE-2026-4724

Undefined behavior in the Audio/Video component. This vulnerability was fixed in Firefox 149 and Thunderbird 149.

EPSS: 0.003 (24.4th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.

Affected products

Mozilla Firefox — versions 149
Mozilla Thunderbird — versions 149

Weakness classification (CWE)

CWE-758

References

security@mozilla.org (Permissions Required)
security@mozilla.org (Vendor Advisory)
security@mozilla.org (Vendor Advisory)

Frequently asked questions

What is CVE-2026-4724?: CVE-2026-4724 is a critical-severity vulnerability in Mozilla Firefox, classified under CWE-758. CVSS score: 9.1/10. Published 2026-03-24.
How severe is CVE-2026-4724?: Critical severity. CVSS v3 base score is 9.1 out of 10.