CVE-2025-6434

Description

The exception page for the HTTPS-Only feature, displayed when a website is opened via HTTP, lacked an anti-clickjacking delay, potentially allowing an attacker to trick a user into granting an exception and loading a webpage over HTTP. This vulnerability affects Firefox < 140.

Category

4.3
CVSS
Severity: Medium
CVSS 3.1 •
EPSS 0.02%
Vendor Advisory mozilla.org
Affected: Mozilla Firefox
Published at:
Updated at:

References

Link Tags
https://bugzilla.mozilla.org/show_bug.cgi?id=1955182 permissions required
https://www.mozilla.org/security/advisories/mfsa2025-51/ vendor advisory

Frequently Asked Questions

What is the severity of CVE-2025-6434?
CVE-2025-6434 has been scored as a medium severity vulnerability.
How to fix CVE-2025-6434?
To fix CVE-2025-6434, 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-2025-6434 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2025-6434 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-2025-6434?
CVE-2025-6434 affects Mozilla Firefox.
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