Use After Free in Mozilla Firefox
CVE-2026-4725
Sandbox escape due to use-after-free in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 149 and Thunderbird 149.
Vulnerability class: Use-After-Free
Published · last modified .
CVSS v3 metric
CVSS v3 base score 10.0 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.004 (35.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 35th percentile — 35.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.004 · change: +0.001
Affected products
- Mozilla Firefox — versions 149
- Mozilla Thunderbird — versions 149
Weakness classification (CWE)
References
- bugzilla.mozilla.org/show_bug.cgi (Permissions Required)
- www.mozilla.org/security/advisories/mfsa2026-20/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2026-23/
Frequently asked questions
- What is CVE-2026-4725?
- CVE-2026-4725 is a critical-severity vulnerability in Mozilla Firefox, classified under Use After Free. CVSS score: 10.0/10. Published 2026-03-24.
- How severe is CVE-2026-4725?
- Critical severity. CVSS v3 base score is 10.0 out of 10.