CVE-2021-39163
Published: 31 August 2021
Summary
CVE-2021-39163 is a low-severity Exposure of Sensitive Information to an Unauthorized Actor (CWE-200) vulnerability in Fedoraproject Fedora. Its CVSS base score is 3.1 (Low).
Operationally, ranked at the 42.0th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2021-0131
Vulnerability details
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…
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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`.
- CWE(s)
Related Threats
No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Defining permitted attribute values and auditing modifications reduces the chance of incorrect authorization outcomes due to tampered or missing labels.
Ensures authorization decisions for external system use are correctly implemented and enforced.
It assists users in evaluating and applying correct authorization decisions when sharing information with external partners.
Session auditing enables detection of unauthorized exposure or access to sensitive information during user activities.
Drives review and correction of flawed authorization logic applied to organizational data.
Annual reviews and proposal scrutiny detect and block matching programs that would expose sensitive data to unauthorized recipients or systems.
Restricts processing strictly to documented authorized uses, mitigating incorrect authorization decisions for sensitive data.
Addresses incorrect authorization by requiring independent verification of results and an opportunity to contest before any adverse action is taken.