CVE-2025-6433

CRITICAL 9.8CVE-2025-6433 · Published 24/06/2025 · updated 30/09/2026

Package	Affected versions	Patched versions
firefox mozilla	`< 140.0`	`140.0`

Description

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 requires "a secure transport established without errors". This vulnerability was fixed in Firefox 140 and Thunderbird 140.

References

bugzilla.mozilla.org/show_bug.cgi · Permissions Required
mozilla.org/security/advisories/mfsa2025-51 · Vendor Advisory
mozilla.org/security/advisories/mfsa2025-54

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