Information disclosure in Mozilla Firefox
CVE-2025-6425
An attacker who enumerated resources from the WebCompat extension could have obtained a persistent UUID that identified the browser, and persisted between containers and normal/private browsing mode, but not profiles. This vulnerability was fixed in Firefox 140, Firefox ESR 115.25, Firefox ESR 128.12, Thunderbird 140, and Thunderbird 128.12.
Vulnerability class: Information Disclosure
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N.
EPSS exploit prediction
EPSS: 0.003 (21.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 22nd percentile — 21.7% 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: 0.003 · change: +0.000
Affected products
- Mozilla Firefox — versions 115.25, 128.12, 140
- Mozilla Thunderbird — versions 128.12, 140
Weakness classification (CWE)
References
- bugzilla.mozilla.org/show_bug.cgi (Issue Tracking, Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2025-51/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2025-52/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2025-53/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2025-54/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2025-55/ (Vendor Advisory)
- af854a3a-2127-422b-91ae-364da2661108
- af854a3a-2127-422b-91ae-364da2661108
Frequently asked questions
- What is CVE-2025-6425?
- CVE-2025-6425 is a medium-severity vulnerability in Mozilla Firefox, classified under Information Disclosure. CVSS score: 4.3/10. Published 2025-06-24.
- How severe is CVE-2025-6425?
- Medium severity. CVSS v3 base score is 4.3 out of 10.