DEBIAN-CVE-2021-29471

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    DEBIAN-CVE-2021-29471

    Published: 11 May 2021Last Modified: 11 Aug 2026
    Upstream:
    CVE-2021-29471

    Summary:

    Details: 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 1.33.2 "Push rules" can specify conditions under which they will match, including `event_match`, which matches event content against a pattern including wildcards. Certain patterns can cause very poor performance in the matching engine, leading to a denial-of-service when processing moderate length events. The issue is patched in version 1.33.2. A potential workaround might be to prevent users from making custom push rules, by blocking such requests at a reverse-proxy.

    References: https://security-tracker.debian.org/tracker/CVE-2021-29471

    Affected packages

    Package

    Name: matrix-synapse

    Purl: pkg:deb/debian/matrix-synapse?arch=source&distro=forky

    Affected ranges

    Type: ECOSYSTEM

    Events:

    Introduced- 0
    Fixed -1.33.2-1

    Affected versions

    0.19.2+dfsg-3
    0.19.2+dfsg-4
    0.19.2+dfsg-5
    0.19.2+dfsg-6

    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
    DEBIAN-CVE-2021-29471 | CVE-DB