CVE-2026-2781: Mozilla Firefox

Critical severity, CVSS 9.8. EPSS: 0.6% chance of exploitation in the next 30 days.

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.

Affected products

• Mozilla Firefox: before 140.8.0 (fixed in 140.8.0); before 148.0 (fixed in 148.0)
• Mozilla Thunderbird: before 140.8.0 (fixed in 140.8.0); before 148.0 (fixed in 148.0)

Published 2026-02-24. Last modified 2026-06-17.