CVE-2025-6433
Published: 24 June 2025
Summary
CVE-2025-6433 is a critical-severity Improper Certificate Validation (CWE-295) vulnerability in Mozilla Firefox. Its CVSS base score is 9.8 (Critical).
Operationally, ranked at the 40.8th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-19088
Vulnerability details
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…
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which requires "a secure transport established without errors". This vulnerability was fixed in Firefox 140 and Thunderbird 140.
- CWE(s)
Related Threats
No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
When certificates are used to establish component provenance, the control requires correct certificate validation procedures.
Mandates approved trust anchors and issuance policies, directly preventing acceptance of unvalidated or untrusted certificates.
Correct system time is required for proper enforcement of certificate notBefore/notAfter dates and time-based revocation checks.