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    <link>https://cve.radiocsirt.org</link>
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      <title>CVE-2021-39163 — Adding a private/unlisted room to a community exposes room metadata in an unauthorised manner.</title>
      <link>https://cve.radiocsirt.org/vuln/cve-2021-39163</link>
      <description>&lt;p&gt;&lt;strong&gt;Affected:&lt;/strong&gt; matrix-org synapse&lt;/p&gt;
&lt;p&gt;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`.&lt;/p&gt;</description>
      <content:encoded>&lt;p&gt;&lt;strong&gt;Affected:&lt;/strong&gt; matrix-org synapse&lt;/p&gt;
&lt;p&gt;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`.&lt;/p&gt;</content:encoded>
      <guid isPermaLink="false">https://cve.radiocsirt.org/vuln/cve-2021-39163</guid>
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    <item>
      <title>GHSA-jj53-8fmw-f2w2 — Adding a private/unlisted room to a community exposes room metadata in an unauthorised manner.</title>
      <link>https://cve.radiocsirt.org/vuln/ghsa-jj53-8fmw-f2w2</link>
      <description>&lt;p&gt;&lt;strong&gt;Affected:&lt;/strong&gt; PyPI: matrix-synapse&lt;/p&gt;
&lt;p&gt;### 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).&lt;/p&gt;
&lt;p&gt;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.&lt;/p&gt;
&lt;p&gt;### Patches
Server administrators should upgrade to 1.41.1 or higher.&lt;/p&gt;
&lt;p&gt;### 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.&lt;/p&gt;
&lt;p&gt;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`&lt;/p&gt;
&lt;p&gt;### References
n/a&lt;/p&gt;
&lt;p&gt;### For more information
If you have any questions or comments about this advisory, e-mail us at security@matrix.org.&lt;/p&gt;</description>
      <content:encoded>&lt;p&gt;&lt;strong&gt;Affected:&lt;/strong&gt; PyPI: matrix-synapse&lt;/p&gt;
&lt;p&gt;### 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).&lt;/p&gt;
&lt;p&gt;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.&lt;/p&gt;
&lt;p&gt;### Patches
Server administrators should upgrade to 1.41.1 or higher.&lt;/p&gt;
&lt;p&gt;### 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.&lt;/p&gt;
&lt;p&gt;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`&lt;/p&gt;
&lt;p&gt;### References
n/a&lt;/p&gt;
&lt;p&gt;### For more information
If you have any questions or comments about this advisory, e-mail us at security@matrix.org.&lt;/p&gt;</content:encoded>
      <guid isPermaLink="false">https://cve.radiocsirt.org/vuln/ghsa-jj53-8fmw-f2w2</guid>
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