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 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.
The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.
The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.
| Link | Tags |
|---|---|
| https://github.com/matrix-org/synapse/commit/cb35df940a | third party advisory patch |
| https://github.com/matrix-org/synapse/releases/tag/v1.41.1 | third party advisory release notes |
| https://github.com/matrix-org/synapse/security/advisories/GHSA-3x4c-pq33-4w3q | third party advisory |
| https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PXT7ID7DNBRN2TVTETU3SYQHJKEG6PXN/ | vendor advisory |
| https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2VHDEPCZ22GJFMZCWA2XZAGPOEV72POF/ | vendor advisory |