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.
Fix
Patch, vendor advisory and mitigation references on NVD 6
- https://bugzilla.mozilla.org/show_bug.cgi?id=1717672 Issue 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
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 1
- First seenCVSS 4.3 · mozillaNVD modified 2026-10-23 22:10
Affected (CPE criteria) 2
cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*
References 8
- https://bugzilla.mozilla.org/show_bug.cgi?id=1717672 Issue 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