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.
CVSS Details
- CVSS 3.1 Base Score: 3.1
- CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Alpine Linux | — | Upgrade synapse | Aug 22, 2024 | Aug 31, 2021 |
| Freebsd | — | Upgrade py36-matrix-synapseUpgrade py39-matrix-synapseUpgrade py38-matrix-synapseUpgrade py37-matrix-synapseUpgrade py310-matrix-synapse | Nov 4, 2022 | Sep 2, 2021 |
| Ubuntu | — | No solution exists | Jun 26, 2025 | Aug 31, 2021 |
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