Vulnerability in Mozilla Firefox
CVE-2025-6433
If a user visited a webpage with an invalid TLS certificate, and granted an exception, the webpage was able to provide a WebAuthn challenge that the user would be prompted to complete. This is in violation of the WebAuthN spec which requi…
Vulnerability class: Improper Certificate Validation
EPSS: 0.002 (15.4th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
Affected products
- Mozilla Firefox — versions 140
- Mozilla Thunderbird — versions 140
Weakness classification (CWE)
References
- security@mozilla.org (Permissions Required)
- security@mozilla.org (Vendor Advisory)
- security@mozilla.org
Frequently asked questions
- What is CVE-2025-6433?
- CVE-2025-6433 is a critical-severity vulnerability in Mozilla Firefox, classified under Improper Certificate Validation. CVSS score: 9.8/10. Published 2025-06-24.
- How severe is CVE-2025-6433?
- Critical severity. CVSS v3 base score is 9.8 out of 10.