Integer overflow in Mozilla Firefox
CVE-2026-2781
Integer overflow in the Libraries component in NSS. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, Thunderbird 140.8, and Firefox ESR 115.35.
Vulnerability class: Integer Overflow
EPSS: 0.004 (27.9th 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 115.35, 140.8, 148
- Mozilla Thunderbird — versions 140.8, 148
Weakness classification (CWE)
References
- security@mozilla.org (Permissions Required, Issue Tracking)
- security@mozilla.org (Vendor Advisory)
- security@mozilla.org (Vendor Advisory)
- security@mozilla.org (Vendor Advisory)
- security@mozilla.org (Vendor Advisory)
- security@mozilla.org
- af854a3a-2127-422b-91ae-364da2661108
Frequently asked questions
- What is CVE-2026-2781?
- CVE-2026-2781 is a critical-severity vulnerability in Mozilla Firefox, classified under Integer Overflow or Wraparound. CVSS score: 9.8/10. Published 2026-02-24.
- How severe is CVE-2026-2781?
- Critical severity. CVSS v3 base score is 9.8 out of 10.