CVE-2025-4083
A process isolation vulnerability in Thunderbird stemmed from improper handling of javascript: URIs, which could allow content to execute in the top-level document's process instead of the intended frame, potentially enabling a sandbox escape.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.43%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
A process isolation vulnerability in Thunderbird stemmed from improper handling of javascript: URIs, which could allow content to execute in the top-level document's process instead of the intended frame, potentially enabling a sandbox escape. This vulnerability was fixed in Firefox 138, Firefox ESR 128.10, Firefox ESR 115.23, Thunderbird 138, and Thunderbird 128.10.
- CVSS 3.1
- 9.1 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
- EPSS
- 0.43% probability · 37th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-653
- Affected
- mozilla/firefox · mozilla/thunderbird
- Source
- security@mozilla.org
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1958350Permissions 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/msg00024.html
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.