CVE-2026-0884

CRITICAL

Mozilla Firefox < 140.7.0 - Use After Free

Title source: rule

Description

Use-after-free in the JavaScript Engine component. This vulnerability affects Firefox < 147, Firefox ESR < 140.7, Thunderbird < 147, and Thunderbird < 140.7.

References (5)

[Permissions Required] https://bugzilla.mozilla.org/show_bug.cgi?id=2003588

[Vendor Advisory] https://www.mozilla.org/security/advisories/mfsa2026-01/

[Vendor Advisory] https://www.mozilla.org/security/advisories/mfsa2026-03/

[Vendor Advisory] https://www.mozilla.org/security/advisories/mfsa2026-04/

[Vendor Advisory] https://www.mozilla.org/security/advisories/mfsa2026-05/

Scores

CVSS v3 9.8

EPSS 0.0003

EPSS Percentile 6.3%

Attack Vector NETWORK

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Classification

CWE

CWE-416

Status published

Affected Products (4)

mozilla/firefox < 140.7.0

mozilla/firefox < 147.0

mozilla/thunderbird < 140.7.0

mozilla/thunderbird < 147.0

Timeline

Published Jan 13, 2026

Tracked Since Feb 18, 2026