CVE-2023-42453

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    CVE-2023-42453

    Published: 26 Sept 2023Last Modified: 12 Aug 2026

    Summary: Improper validation of receipts allows forged read receipts in matrix synapse

    Details: 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.

    References: 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://github.com/CVEProject/cvelistV5/tree/main/cves/2023/42xxx/CVE-2023-42453.json, https://github.com/matrix-org/synapse/security/advisories/GHSA-7565-cq32-vx2x, https://nvd.nist.gov/vuln/detail/CVE-2023-42453, https://security.gentoo.org/glsa/202401-12, https://github.com/matrix-org/synapse/pull/16327

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: GIT

    Events:

    Introduced- d731b75c7bcada708f1acbb83e2521da6a7d97a9
    Fixed -88ba67eb91215a708f321e16559fe3c2c0d0a407

    Affected versions

    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
    CVE-2023-42453 | CVE-DB