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    CVE-2025-6434

    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.

    Published:Jun 24, 2025
    Last Modified:Apr 20, 2026
    EPS:Jun 24, 2025
    EPSS Score:0.00171
    CVSS Score:4.3

    Affected Products

    Vendor
    Mozilla
    Product
    Firefox

    Exploits

    No exploit reference

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    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High