CVE-2021-39164
Published: 31 August 2021
Summary
CVE-2021-39164 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 in the top 49.1% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2021-0132
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 membership (list of members, with their display names) of a room if they know the ID of…
more
the room. The vulnerability is limited to rooms with `shared` history visibility. Furthermore, the unauthorised user must be using an account on a vulnerable homeserver that is in the room. Server administrators should upgrade to 1.41.1 or later in order to receive the patch. One workaround is available. Administrators of servers that use a reverse proxy could, with potentially unacceptable loss of functionality, block the endpoints: `/_matrix/client/r0/rooms/{room_id}/members` with `at` query parameter, and `/_matrix/client/unstable/rooms/{room_id}/members` with `at` query parameter.
- 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.