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.
Does this matter?
Lower severity and a low EPSS score (0.27%). Track it; it rarely justifies an emergency change on its own.
Description
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.
- CVSS 3.1
- 4.3 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
- EPSS
- 0.27% probability · 20th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-200
- Affected
- mozilla/firefox
- Source
- security@mozilla.org
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1717672Issue Tracking, Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2025-51/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2025-52/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2025-53/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2025-54/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2025-55/Vendor Advisory
- https://lists.debian.org/debian-lts-announce/2025/06/msg00029.html
- https://lists.debian.org/debian-lts-announce/2025/07/msg00002.html
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.