CVE-2025-4083

moderate-risk
Published 2025-04-29

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.

Do I need to act?

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0.41% chance of exploitation
EPSS score — low exploit probability
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Not on CISA KEV list
No confirmed active exploitation reported to CISA
?
Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
9
CVSS 9.1/10 Critical
NETWORK / LOW complexity

Affected Products (4)

Affected Vendors

Mozilla

References (7)

Permissions Required https://bugzilla.mozilla.org/show_bug.cgi?id=1958350
Vendor Advisory 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/
https://lists.debian.org/debian-lts-announce/2025/05/msg00024.html
43
/ 100
moderate-risk
Severity 31/34 · Critical
Exploitability 2/34 · Minimal
Exposure 10/34 · Low