DEBIAN-CVE-2021-21273

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    DEBIAN-CVE-2021-21273

    Published: 26 Feb 2021Last Modified: 11 Aug 2026
    Upstream:
    CVE-2021-21273

    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 1.25.0, requests to user provided domains were not restricted to external IP addresses when calculating the key validity for third-party invite events and sending push notifications. This could cause Synapse to make requests to internal infrastructure. The type of request was not controlled by the user, although limited modification of request bodies was possible. For the most thorough protection server administrators should remove the deprecated `federation_ip_range_blacklist` from their settings after upgrading to Synapse v1.25.0 which will result in Synapse using the improved default IP address restrictions. See the new `ip_range_blacklist` and `ip_range_whitelist` settings if more specific control is necessary.

    References: https://security-tracker.debian.org/tracker/CVE-2021-21273

    Affected packages

    Package

    Name: matrix-synapse

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

    Affected ranges

    Type: ECOSYSTEM

    Events:

    Introduced- 0
    Fixed -1.25.0-1

    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-2021-21273 | CVE-DB