Use After Free in Mozilla Firefox
CVE-2026-8953
Sandbox escape due to use-after-free in the Disability Access APIs component. This vulnerability was fixed in Firefox 151, Firefox ESR 115.36, Firefox ESR 140.11, Thunderbird 151, and Thunderbird 140.11.
Vulnerability class: Use-After-Free
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.6 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.005 (37.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 37th percentile — 37.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: -0.001
Affected products
- Mozilla Firefox — versions 115.36, 140.11, 151
- Mozilla Thunderbird — versions 140.11, 151
Weakness classification (CWE)
References
- bugzilla.mozilla.org/show_bug.cgi (Permissions Required)
- www.mozilla.org/security/advisories/mfsa2026-46/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-47/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-48/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-50/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-51/ (Vendor Advisory)
Frequently asked questions
- What is CVE-2026-8953?
- CVE-2026-8953 is a critical-severity vulnerability in Mozilla Firefox, classified under Use After Free. CVSS score: 9.6/10. Published 2026-05-19.
- How severe is CVE-2026-8953?
- Critical severity. CVSS v3 base score is 9.6 out of 10.