CVE-2025-2817
Thunderbird's update mechanism allowed a medium-integrity user process to interfere with the SYSTEM-level updater by manipulating the file-locking behavior.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.63%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
Thunderbird's update mechanism allowed a medium-integrity user process to interfere with the SYSTEM-level updater by manipulating the file-locking behavior. By injecting code into the user-privileged process, an attacker could bypass intended access controls, allowing SYSTEM-level file operations on paths controlled by a non-privileged user and enabling privilege escalation. This vulnerability was fixed in Firefox 138, Firefox ESR 128.10, Firefox ESR 115.23, Thunderbird 138, and Thunderbird 128.10.
- CVSS 3.1
- 8.8 HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 0.63% probability · 48th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-22
- Affected
- mozilla/firefox · mozilla/thunderbird
- Source
- security@mozilla.org
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1917536Permissions Required
- https://www.mozilla.org/security/advisories/mfsa2025-28/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2025-29/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2025-30/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2025-31/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2025-32/Vendor Advisory
- https://lists.debian.org/debian-lts-announce/2025/05/msg00022.html
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.