Critical severity · published Feb 24, 2026
CVE-2026-2781
Integer overflow in the Libraries component in NSS
9.8
CVSS
0.4%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 37% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
FI
Firefox · Mozilla
before 140.8.0; before 148.0 · source: NVD
TH
Thunderbird · Mozilla
before 140.8.0; before 148.0 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-2781
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-2781
Issue Tracking
https://bugzilla.mozilla.org/show_bug.cgi?id=2009552
Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-13/
Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-15/
Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-16/
Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-17/
www.mozilla.org
https://www.mozilla.org/security/advisories/mfsa2026-31/
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