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Security Advisories: MDE2OlNlY3VyaXR5QWR2aXNvcnlHSFNBLWpqNTMtOGZtdy1mMncy
Adding a private/unlisted room to a community exposes room metadata in an unauthorised manner.
Impact
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.
Patches
Server administrators should upgrade to 1.41.1 or higher.
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 following endpoints:
/_matrix/client/r0/groups/{group_id}/rooms
/_matrix/client/unstable/groups/{group_id}/rooms
References
n/a
For more information
If you have any questions or comments about this advisory, e-mail us at [email protected].
Permalink: https://github.com/advisories/GHSA-jj53-8fmw-f2w2JSON: https://advisories.ecosyste.ms/api/v1/advisories/MDE2OlNlY3VyaXR5QWR2aXNvcnlHSFNBLWpqNTMtOGZtdy1mMncy
Source: GitHub Advisory Database
Origin: Unspecified
Severity: Low
Classification: General
Published: almost 3 years ago
Updated: over 1 year ago
CVSS Score: 3.1
CVSS vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
Identifiers: GHSA-jj53-8fmw-f2w2, CVE-2021-39163
References:
- https://github.com/matrix-org/synapse/security/advisories/GHSA-jj53-8fmw-f2w2
- https://github.com/matrix-org/synapse/commit/cb35df940a
- https://github.com/matrix-org/synapse/releases/tag/v1.41.1
- https://nvd.nist.gov/vuln/detail/CVE-2021-39163
- https://lists.fedoraproject.org/archives/list/[email protected]/message/PXT7ID7DNBRN2TVTETU3SYQHJKEG6PXN/
- https://lists.fedoraproject.org/archives/list/[email protected]/message/2VHDEPCZ22GJFMZCWA2XZAGPOEV72POF/
- https://github.com/advisories/GHSA-jj53-8fmw-f2w2
Blast Radius: 4.4
Affected Packages
pypi:matrix-synapse
Dependent packages: 6Dependent repositories: 26
Downloads: 19,885 last month
Affected Version Ranges: < 1.41.1
Fixed in: 1.41.1
All affected versions: 0.33.5, 0.33.6, 0.33.7, 0.33.8, 0.33.9, 0.34.0, 0.99.0, 0.99.1, 0.99.2, 0.99.3, 0.99.4, 0.99.5, 1.0.0, 1.1.0, 1.2.0, 1.2.1, 1.3.0, 1.3.1, 1.4.0, 1.4.1, 1.5.0, 1.5.1, 1.6.0, 1.6.1, 1.7.0, 1.7.1, 1.7.2, 1.7.3, 1.8.0, 1.9.0, 1.9.1, 1.10.0, 1.10.1, 1.11.0, 1.11.1, 1.12.0, 1.12.1, 1.12.2, 1.12.3, 1.12.4, 1.13.0, 1.14.0, 1.15.0, 1.15.1, 1.15.2, 1.16.0, 1.16.1, 1.17.0, 1.18.0, 1.19.0, 1.19.1, 1.19.2, 1.19.3, 1.20.0, 1.20.1, 1.21.0, 1.21.1, 1.21.2, 1.22.0, 1.22.1, 1.23.0, 1.23.1, 1.24.0, 1.25.0, 1.26.0, 1.27.0, 1.28.0, 1.29.0, 1.30.0, 1.30.1, 1.31.0, 1.32.0, 1.32.1, 1.32.2, 1.33.0, 1.33.1, 1.33.2, 1.34.0, 1.35.0, 1.35.1, 1.36.0, 1.37.0, 1.37.1, 1.38.0, 1.38.1, 1.39.0, 1.40.0, 1.41.0
All unaffected versions: 1.41.1, 1.42.0, 1.43.0, 1.44.0, 1.45.0, 1.45.1, 1.46.0, 1.47.0, 1.47.1, 1.48.0, 1.49.0, 1.49.2, 1.50.0, 1.50.1, 1.50.2, 1.51.0, 1.52.0, 1.53.0, 1.54.0, 1.55.0, 1.55.1, 1.55.2, 1.56.0, 1.57.0, 1.57.1, 1.58.0, 1.58.1, 1.59.0, 1.59.1, 1.60.0, 1.61.0, 1.61.1, 1.62.0, 1.63.0, 1.63.1, 1.64.0, 1.65.0, 1.66.0, 1.67.0, 1.68.0, 1.69.0, 1.70.0, 1.70.1, 1.71.0, 1.72.0, 1.73.0, 1.74.0, 1.75.0, 1.76.0, 1.77.0, 1.78.0, 1.79.0, 1.80.0, 1.81.0, 1.82.0, 1.83.0, 1.84.0, 1.84.1, 1.85.0, 1.85.1, 1.85.2, 1.86.0, 1.87.0, 1.88.0, 1.89.0, 1.90.0, 1.91.0, 1.91.1, 1.91.2, 1.92.1, 1.92.2, 1.92.3, 1.93.0, 1.94.0, 1.95.0, 1.95.1, 1.96.1, 1.97.0, 1.98.0, 1.99.0, 1.100.0, 1.101.0, 1.102.0, 1.103.0, 1.104.0, 1.105.0, 1.105.1, 1.106.0, 1.107.0, 1.108.0, 1.109.0, 1.110.0, 1.111.0