Vulnerability in Mozilla Firefox

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 esc…

EPSS: 0.004 (32.3th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2025-4083?
CVE-2025-4083 is a critical-severity vulnerability in Mozilla Firefox, classified under CWE-653. CVSS score: 9.1/10. Published 2025-04-29.
How severe is CVE-2025-4083?
Critical severity. CVSS v3 base score is 9.1 out of 10.
Is CVE-2025-4083 known to be exploited?
2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.