Buffer overflow in Mozilla Firefox and Firefox for Android - CVE-2026-12318

Vulnerability identifier: #VU134640

CSH Severity: Low

CVSS v4: 4.6 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-12318

CWE-ID: CWE-119

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to incorrect boundary conditions in the Libraries component in NSS when parsing input. A remote attacker can supply crafted input to cause a denial of service.

Mozilla Firefox
Firefox for Android
Ubuntu
Mozilla Thunderbird
nss (Ubuntu package)

Install security update from vendor's website.

Mozilla Firefox - update to 152.0
Firefox for Android - update to 152.0
Mozilla Thunderbird - update to 152.0
nss (Ubuntu package) - addressed in versions 2:3.98-0ubuntu0.22.04.4, 2:3.98-1ubuntu0.2, 2:3.114-1ubuntu0.2, 2:3.120-1ubuntu2.1

• https://www.mozilla.org/en-US/security/advisories/mfsa2026-57/
• https://bugzilla.mozilla.org/show_bug.cgi?id=2023478

• Multiple vulnerabilities in Mozilla Firefox
• Multiple vulnerabilities in Mozilla Thunderbird
• Ubuntu update for nss