Is CVE-2025-6433 actively exploited?

No active exploitation of CVE-2025-6433 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2025-6433 be exploited remotely?

Yes. CVE-2025-6433 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2025-6433?

CVE-2025-6433 has a CVSS score of 9.8 (CRITICAL).

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CRITICAL

CVE-2025-6433

CWE-295Published: June 24, 2025· Updated: Jun 17, 2026

9.8

CVSS v3.1

Official 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.

NVD Source

Technical Analysis

CVE-2025-6433 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.