Vulnerability in Mozilla Firefox
CVE-2026-4718
Undefined behavior in the WebRTC: Signaling component. This vulnerability was fixed in Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.
EPSS: 0.003 (21.9th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N.
Affected products
- Mozilla Firefox — versions 140.9, 149
- Mozilla Thunderbird — versions 140.9, 149
Weakness classification (CWE)
References
- security@mozilla.org (Permissions Required)
- security@mozilla.org (Vendor Advisory)
- security@mozilla.org (Vendor Advisory)
- security@mozilla.org (Vendor Advisory)
- security@mozilla.org (Vendor Advisory)
Frequently asked questions
- What is CVE-2026-4718?
- CVE-2026-4718 is a high-severity vulnerability in Mozilla Firefox, classified under CWE-758. CVSS score: 8.1/10. Published 2026-03-24.
- How severe is CVE-2026-4718?
- High severity. CVSS v3 base score is 8.1 out of 10.