CVE-2025-4085: Potential information leakage and privilege escalation in UITour actor

Severity: high (CVSS 7.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-04-29 · updated 2026-09-30
Weakness: CWE-269

Description

An attacker with control over a content process could potentially leverage the privileged UITour actor to leak sensitive information or escalate privileges. This vulnerability was fixed in Firefox 138 and Thunderbird 138.

Affected products

Mozilla Firefox: before 138.0 — fixed in 138.0
Mozilla Thunderbird: before 138.0 — fixed in 138.0

How to fix

Upgrade to a fixed version: Mozilla Firefox 138.0; Mozilla Thunderbird 138.0. Check the vendor advisory for mitigations.

References

https://bugzilla.mozilla.org/show_bug.cgi?id=1915280
https://www.mozilla.org/security/advisories/mfsa2025-28/
https://www.mozilla.org/security/advisories/mfsa2025-31/

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