PYSEC-2026-845

    Dashboard / Vulnerabilities / PYSEC-2026-845

    PYSEC-2026-845

    Published: 6 Jul 2026Last Modified: 7 Jul 2026

    Summary: Matrix Synapse Improper Signature Validation

    Details: Matrix Synapse before 0.33.3.1 and 0.33.2.1 allows remote attackers to spoof events and possibly have unspecified other impacts by leveraging improper transaction and event signature validation.

    References: https://nvd.nist.gov/vuln/detail/CVE-2018-16515, https://github.com/matrix-org/synapse/issues/3796#event-1833126269, https://github.com/matrix-org/synapse/commit/5bf8bc79ebc22c61968f2eb487714813fccbdb9b, https://github.com/matrix-org/synapse/commit/804dd41e18c449e711e443398b95c9f6c68b6fa2, https://github.com/matrix-org/synapse/commit/a5a0bf5cf71caed3c4e3677d2bce667c147dadfc, https://github.com/matrix-org/synapse/commit/c127c8d0421f0228a46ebbe280c9537e8d8ea42b, https://github.com/matrix-org/synapse, https://lists.fedoraproject.org/archives/list/[email protected]/message/IRW7YR2H3ASUSYX4AO4KMY3FNVDNYW3P, https://matrix.org/blog/2018/09/06/critical-security-update-synapse-0-33-3-1, https://pypi.org/project/matrix-synapse, https://github.com/advisories/GHSA-fmvh-rvq5-hhjx

    Affected packages

    Package

    Name: matrix-synapse

    Purl: pkg:pypi/matrix-synapse

    Affected ranges

    Type: ECOSYSTEM

    Events:

    Introduced- 0
    Fixed -0.33.2.1

    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
    PYSEC-2026-845 | CVE-DB