VulnerabilityModified

CVE-2026-16389

Incorrect boundary conditions, integer overflow in the Libraries component in NSS.

CRITICAL 9.8EPSS 0.56%

Does this matter?

High impact if exploited, but EPSS currently rates exploitation as unlikely (0.56%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.

Description

Incorrect boundary conditions, integer overflow in the Libraries component in NSS. This vulnerability was fixed in Firefox 153 and Thunderbird 153.

CVSS 3.1: 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS: 0.56% probability · 45th percentile
CISA KEV: Not listed
Weakness: CWE-190
Affected: mozilla/firefox · mozilla/thunderbird
Source: security@mozilla.org

References

https://bugzilla.mozilla.org/show_bug.cgi?id=2043887Permissions Required
https://www.mozilla.org/security/advisories/mfsa2026-68/Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-71/Vendor Advisory
https://lists.debian.org/debian-lts-announce/2026/08/msg00019.html

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.