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    CVE-2023-42453

    Synapse is an open-source Matrix homeserver written and maintained by the Matrix.org Foundation. Users were able to forge read receipts for any event (if they knew the room ID and event ID). Note that the users were not able to view the events, but simply mark it as read. This could be confusing as clients will show the event as read by the user, even if they are not in the room. This issue has been patched in version 1.93.0. Users are advised to upgrade. There are no known workarounds for this issue.

    Published:Sep 26, 2023
    Last Modified:Jun 18, 2025
    EPS:Sep 26, 2023
    EPSS Score:0.00127
    CVSS Score:3.1

    Affected Products

    Vendor
    Fedoraproject
    Product
    Fedora
    Vendor
    Matrix
    Product
    Synapse

    Exploits

    No exploit reference

    Common Weakness Enumeration

    CWE-285 Improper Authorization

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    References

    https://github.com/matrix-org/synapse/pull/16327
    https://github.com/matrix-org/synapse/security/advisories/GHSA-7565-cq32-vx2x
    https://lists.fedoraproject.org/archives/list/[email protected]/message/2AFB2Y3S2VCPCN5P2XCZTG24MBMZ7DM4/
    https://lists.fedoraproject.org/archives/list/[email protected]/message/65QPC55I4D27HIZP7H2NQ34EOXHPP4AO/
    https://lists.fedoraproject.org/archives/list/[email protected]/message/N6P4QULVUE254WI7XF2LWWOGHCYVFXFY/
    https://security.gentoo.org/glsa/202401-12
    https://github.com/matrix-org/synapse/pull/16327
    https://github.com/matrix-org/synapse/security/advisories/GHSA-7565-cq32-vx2x
    https://lists.fedoraproject.org/archives/list/[email protected]/message/2AFB2Y3S2VCPCN5P2XCZTG24MBMZ7DM4/
    https://lists.fedoraproject.org/archives/list/[email protected]/message/65QPC55I4D27HIZP7H2NQ34EOXHPP4AO/
    https://lists.fedoraproject.org/archives/list/[email protected]/message/N6P4QULVUE254WI7XF2LWWOGHCYVFXFY/
    https://security.gentoo.org/glsa/202401-12

    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