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.
Administrators of servers that use a reverse proxy could, with potentially unacceptable loss of functionality, block the following endpoints:
* /_matrix/client/r0/rooms/{room_id}/members
with at
query parameter
* /_matrix/client/unstable/rooms/{room_id}/members
with at
query parameter
n/a
If you have any questions or comments about this advisory, e-mail us at security@matrix.org.
{ "nvd_published_at": "2021-08-31T17:15:00Z", "cwe_ids": [ "CWE-200" ], "severity": "LOW", "github_reviewed": true, "github_reviewed_at": "2021-08-31T19:13:32Z" }