CVE-2025-6434

MEDIUM

Firefox < 140.0 - Clickjacking via HTTPS-Only Exception Page

Title source: llm
STIX 2.1

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 was fixed in Firefox 140 and Thunderbird 140.

References (3)

Core 3

Scores

CVSS v3 4.3
EPSS 0.0023
EPSS Percentile 13.4%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

CISA SSVC

Vulnrichment
Exploitation none
Automatable no
Technical Impact partial

Details

CWE
CWE-1021
Status published
Products (3)
mozilla/firefox < 140.0
Mozilla/Firefox 140
Mozilla/Thunderbird 140
Published Jun 24, 2025
Tracked Since Feb 18, 2026