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    CVE-2025-6427

    An attacker was able to bypass the `connect-src` directive of a Content Security Policy by manipulating subdocuments. This would have also hidden the connections from the Network tab in Devtools. 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:0.00317
    CVSS Score:9.1

    Affected Products

    Vendor
    Mozilla
    Product
    Firefox

    Exploits

    No exploit reference

    Common Weakness Enumeration

    CWE-693 Protection Mechanism Failure

    Common Attack Pattern Enumeration and Classification (CAPEC)

    CAPEC-1 Accessing Functionality Not Properly Constrained by ACLs
    CAPEC-107 Cross Site Tracing
    CAPEC-127 Directory Indexing
    CAPEC-17 Using Malicious Files
    CAPEC-20 Encryption Brute Forcing
    CAPEC-22 Exploiting Trust in Client
    CAPEC-237 Escaping a Sandbox by Calling Code in Another Language
    CAPEC-36 Using Unpublished Interfaces or Functionality
    CAPEC-477 Signature Spoofing by Mixing Signed and Unsigned Content
    CAPEC-480 Escaping Virtualization
    CAPEC-51 Poison Web Service Registry
    CAPEC-57 Utilizing REST's Trust in the System Resource to Obtain Sensitive Data
    CAPEC-59 Session Credential Falsification through Prediction
    CAPEC-65 Sniff Application Code
    CAPEC-668 Key Negotiation of Bluetooth Attack (KNOB)
    CAPEC-74 Manipulating State
    CAPEC-87 Forceful Browsing

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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