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.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Mozilla Firefox
115.25 to ≤ 115.*unaffected128.12 to ≤ 128.*unaffected140 to ≤ *unaffected
Mozilla Thunderbird
128.12 to ≤ 128.*unaffected140 to ≤ *unaffected
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1717672 ↗
- https://www.mozilla.org/security/advisories/mfsa2025-51/ ↗
- https://www.mozilla.org/security/advisories/mfsa2025-52/ ↗
- https://www.mozilla.org/security/advisories/mfsa2025-53/ ↗
- https://www.mozilla.org/security/advisories/mfsa2025-54/ ↗
- https://www.mozilla.org/security/advisories/mfsa2025-55/ ↗
- https://lists.debian.org/debian-lts-announce/2025/07/msg00002.html ↗
- https://lists.debian.org/debian-lts-announce/2025/06/msg00029.html ↗