Privilege escalation in Mozilla Firefox
CVE-2025-4085
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.
Vulnerability class: Privilege Escalation
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N.
EPSS exploit prediction
EPSS: 0.003 (20.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 21st percentile — 20.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: +0.000
Affected products
- Mozilla Firefox — versions 138
- Mozilla Thunderbird — versions 138
Weakness classification (CWE)
Public proof-of-concept exploits
References
- bugzilla.mozilla.org/show_bug.cgi (Permissions Required)
- www.mozilla.org/security/advisories/mfsa2025-28/ (Vendor Advisory)
- www.mozilla.org/security/advisories/mfsa2025-31/ (Vendor Advisory)
Frequently asked questions
- What is CVE-2025-4085?
- CVE-2025-4085 is a high-severity vulnerability in Mozilla Firefox, classified under Improper Privilege Management. CVSS score: 7.1/10. Published 2025-04-29.
- How severe is CVE-2025-4085?
- High severity. CVSS v3 base score is 7.1 out of 10.
- Is CVE-2025-4085 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.