DEBIAN-CVE-2021-21394

    Dashboard / Vulnerabilities / DEBIAN-CVE-2021-21394

    DEBIAN-CVE-2021-21394

    Published: 12 Apr 2021Last Modified: 11 Aug 2026
    Upstream:
    CVE-2021-21394

    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 1.28.0 Synapse is missing input validation of some parameters on the endpoints used to confirm third-party identifiers could cause excessive use of disk space and memory leading to resource exhaustion. Note that the groups feature is not part of the Matrix specification and the chosen maximum lengths are arbitrary. Not all clients might abide by them. Refer to referenced GitHub security advisory for additional details including workarounds.

    References: https://security-tracker.debian.org/tracker/CVE-2021-21394

    Affected packages

    Package

    Name: matrix-synapse

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

    Affected ranges

    Type: ECOSYSTEM

    Events:

    Introduced- 0
    Fixed -1.28.0-1

    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-2021-21394 | CVE-DB