Buffer overflow in Mozilla Firefox
CVE-2025-11721
Memory safety bug present in Firefox 143 and Thunderbird 143. This bug showed evidence of memory corruption and we presume that with enough effort this could have been exploited to run arbitrary code. This vulnerability was fixed in Firefo…
Vulnerability class: Buffer Overflow
EPSS: 0.003 (25.0th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
Affected products
- Mozilla Firefox — versions 144
- Mozilla Thunderbird — versions 144
Weakness classification (CWE)
References
- security@mozilla.org (Permissions Required, Issue Tracking)
- security@mozilla.org (Vendor Advisory)
- security@mozilla.org (Vendor Advisory)
Frequently asked questions
- What is CVE-2025-11721?
- CVE-2025-11721 is a critical-severity vulnerability in Mozilla Firefox, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 9.8/10. Published 2025-10-14.
- How severe is CVE-2025-11721?
- Critical severity. CVSS v3 base score is 9.8 out of 10.