CVE-2025-6434mediumCWE-1021

CVE-2025-6434: medium-severity vulnerability in Mozilla Firefox

HTTPS-Only exception screen lacked anti-clickjacking delay

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13Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 4.3epss 0.3%
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 was fixed in Firefox 140 and Thunderbird 140.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
Affected products
Mozilla · FirefoxMozilla · Thunderbird
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