CVE-2026-6772: Incorrect boundary conditions in the Libraries component in NSS

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-04-21 · updated 2026-10-26
Weakness: CWE-754

Description

Incorrect boundary conditions in the Libraries component in NSS. This vulnerability was fixed in Firefox 150, Firefox ESR 115.35, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.

Affected products

Mozilla Firefox: before 115.35.0; before 150.0; from 140.0 before 140.10.0 — fixed in 115.35.0, 150.0, 140.10.0
Mozilla Thunderbird: before 140.10.0 — fixed in 140.10.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 115.35.0, 150.0, 140.10.0; Mozilla Thunderbird 140.10.0. Check the vendor advisory for mitigations.

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2026089
https://www.mozilla.org/security/advisories/mfsa2026-30/
https://www.mozilla.org/security/advisories/mfsa2026-31/
https://www.mozilla.org/security/advisories/mfsa2026-32/
https://www.mozilla.org/security/advisories/mfsa2026-33/
https://www.mozilla.org/security/advisories/mfsa2026-34/

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