CVE-2025-6433

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 affects Firefox < 140.

Category

9.8
CVSS
Severity: Critical
CVSS 3.1 •
EPSS 0.01%
Vendor Advisory mozilla.org
Affected: Mozilla Firefox
Published at:
Updated at:

References

Link Tags
https://bugzilla.mozilla.org/show_bug.cgi?id=1954033 permissions required
https://www.mozilla.org/security/advisories/mfsa2025-51/ vendor advisory

Frequently Asked Questions

What is the severity of CVE-2025-6433?
CVE-2025-6433 has been scored as a critical severity vulnerability.
How to fix CVE-2025-6433?
To fix CVE-2025-6433, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2025-6433 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2025-6433 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2025-6433?
CVE-2025-6433 affects Mozilla Firefox.
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