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    CVE-2021-21392

    Synapse is a Matrix reference homeserver written in python (pypi package matrix-synapse). Matrix is an ecosystem for open federated Instant Messaging and VoIP. In Synapse before version 1.28.0 requests to user provided domains were not restricted to external IP addresses when transitional IPv6 addresses were used. Outbound requests to federation, identity servers, when calculating the key validity for third-party invite events, sending push notifications, and generating URL previews are affected. This could cause Synapse to make requests to internal infrastructure on dual-stack networks. See referenced GitHub security advisory for details and workarounds.

    Published:Apr 12, 2021
    Last Modified:Nov 21, 2024
    EPS:Apr 12, 2021
    EPSS Score:0.002
    CVSS Score:6.3

    Affected Products

    Vendor
    Fedoraproject
    Product
    Fedora
    Vendor
    Matrix
    Product
    Synapse

    Exploits

    No exploit reference

    Common Attack Pattern Enumeration and Classification (CAPEC)

    CAPEC-178 Cross-Site Flashing

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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