🔐 CVE Alert

CVE-2025-6434

MEDIUM 4.3

HTTPS-Only exception screen lacked anti-clickjacking delay

CVSS Score
4.3
EPSS Score
0.0%
EPSS Percentile
0th

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.

Vendor mozilla
Product firefox
Ecosystems
Industries
Technology
Published Jun 24, 2025
Last Updated Apr 13, 2026
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Affected Versions

Mozilla / Firefox
All versions affected
Mozilla / Thunderbird
All versions affected

References

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

Credits

hafiizh & kang ali