Information Exposure Affecting matrix-synapse package, versions <1.41.1-1


Severity

Recommended
0.0
low
0
10

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Threat Intelligence

EPSS
0.14% (51st percentile)

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  • Snyk IDSNYK-DEBIANUNSTABLE-MATRIXSYNAPSE-1577306
  • published1 Sept 2021
  • disclosed31 Aug 2021

Introduced: 31 Aug 2021

CVE-2021-39163  (opens in a new tab)
CWE-200  (opens in a new tab)

How to fix?

Upgrade Debian:unstable matrix-synapse to version 1.41.1-1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream matrix-synapse package and not the matrix-synapse package as distributed by Debian. See How to fix? for Debian:unstable relevant fixed versions and status.

Matrix is an ecosystem for open federated Instant Messaging and Voice over IP. In versions 1.41.0 and prior, unauthorised users can access the name, avatar, topic and number of members of a room if they know the ID of the room. This vulnerability is limited to homeservers where the vulnerable homeserver is in the room and untrusted users are permitted to create groups (communities). By default, only homeserver administrators can create groups. However, homeserver administrators can already access this information in the database or using the admin API. As a result, only homeservers where the configuration setting enable_group_creation has been set to true are impacted. Server administrators should upgrade to 1.41.1 or higher to patch the vulnerability. There are two potential workarounds. Server administrators can set enable_group_creation to false in their homeserver configuration (this is the default value) to prevent creation of groups by non-administrators. Administrators that are using a reverse proxy could, with partial loss of group functionality, block the endpoints /_matrix/client/r0/groups/{group_id}/rooms and /_matrix/client/unstable/groups/{group_id}/rooms.

CVSS Scores

version 3.1