CVE-2025-6434

HTTPS-Only exception screen lacked anti-clickjacking delay

CVSS 4.3 MEDIUMEPSS 0.2%CWE-1021

Vexday Risk Score

13Low

SSVC decision (CISA)

Track

No exploitation signal → monitor

CVSS 4.3EPSS 0.2%KEV nãoPoC —Nuclei —Metasploit —Patch —

Lifecycle

24 Jun 2025Published on NVD

Recommendation: Monitor — no exploitation signal at the moment.

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 · Firefox Mozilla · Thunderbird

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References

https://bugzilla.mozilla.org/show_bug.cgi?id=1955182 https://www.mozilla.org/security/advisories/mfsa2025-51/https://www.mozilla.org/security/advisories/mfsa2025-54/