Use After Free in Mozilla Firefox
CVE-2026-2786
Use-after-free in the JavaScript Engine component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.
Vulnerability class: Use-After-Free
EPSS: 0.000 (5.7th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
Affected products
- Mozilla Firefox — versions 140.8, 148
- Mozilla Thunderbird — versions 140.8, 148
Weakness classification (CWE)
References
- security@mozilla.org (Permissions Required, Issue Tracking)
- security@mozilla.org (Vendor Advisory)
- security@mozilla.org (Vendor Advisory)
- security@mozilla.org (Vendor Advisory)
- security@mozilla.org (Vendor Advisory)
Frequently asked questions
- What is CVE-2026-2786?
- CVE-2026-2786 is a critical-severity vulnerability in Mozilla Firefox, classified under Use After Free. CVSS score: 9.8/10. Published 2026-02-24.
- How severe is CVE-2026-2786?
- Critical severity. CVSS v3 base score is 9.8 out of 10.