Buffer overflow in Mozilla Firefox
CVE-2026-7321
Sandbox escape due to incorrect boundary conditions in the WebRTC: Networking component. This vulnerability was fixed in Firefox 150, Thunderbird 150, Firefox ESR 140.10.1, and Thunderbird 140.10.1.
Vulnerability class: Buffer Overflow
EPSS: 0.000 (15.7th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 9.6 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H.
Affected products
- Mozilla Firefox — versions 140.10.1, 150
- Mozilla Thunderbird — versions 140.10.1, 150
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-2026-7321?
- CVE-2026-7321 is a critical-severity vulnerability in Mozilla Firefox, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 9.6/10. Published 2026-04-28.
- How severe is CVE-2026-7321?
- Critical severity. CVSS v3 base score is 9.6 out of 10.