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
EPSS: 0.002 (16.1th percentile) — read the EPSS interpretation.
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.
Affected products
- Mozilla Firefox — versions 115.25, 128.12, 140
- Mozilla Thunderbird — versions 128.12, 140
Weakness classification (CWE)
References
- security@mozilla.org (Issue Tracking, Vendor Advisory)
- security@mozilla.org (Vendor Advisory)
- security@mozilla.org (Vendor Advisory)
- security@mozilla.org (Vendor Advisory)
- security@mozilla.org (Vendor Advisory)
- security@mozilla.org (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.