Use After Free in Mozilla Firefox
CVE-2025-1009
An attacker could have caused a use-after-free via crafted XSLT data, leading to a potentially exploitable crash. This vulnerability was fixed in Firefox 135, Firefox ESR 115.20, Firefox ESR 128.7, Thunderbird 128.7, and Thunderbird 135.
Vulnerability class: Use-After-Free
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.012 (67.3th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 67th percentile — 67.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.012 · newest: 0.012 · change: -0.000
Affected products
- Mozilla Firefox — versions 115.20, 128.7, 135
- Mozilla Thunderbird — versions 128.7, 135
Weakness classification (CWE)
Public proof-of-concept exploits
References
- bugzilla.mozilla.org/show_bug.cgi (Permissions Required)
- www.mozilla.org/security/advisories/mfsa2025-07/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2025-08/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2025-09/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2025-10/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2025-11/ (Vendor Advisory)
- af854a3a-2127-422b-91ae-364da2661108
- af854a3a-2127-422b-91ae-364da2661108
Frequently asked questions
- What is CVE-2025-1009?
- CVE-2025-1009 is a critical-severity vulnerability in Mozilla Firefox, classified under Use After Free. CVSS score: 9.8/10. Published 2025-02-04.
- How severe is CVE-2025-1009?
- Critical severity. CVSS v3 base score is 9.8 out of 10.
- Is CVE-2025-1009 known to be exploited?
- 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.