CVE-2021-39164
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.
Does this matter?
Lower severity and a low EPSS score (1.46%). Track it; it rarely justifies an emergency change on its own.
Description
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 3.1
- 3.1 LOWCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
- EPSS
- 1.46% probability · 72th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-200, CWE-863
- Affected
- matrix/synapse · fedoraproject/fedora
- Source
- security-advisories@github.com
References
- https://github.com/matrix-org/synapse/commit/cb35df940aPatch, Third Party Advisory
- https://github.com/matrix-org/synapse/releases/tag/v1.41.1Release Notes, Third Party Advisory
- https://github.com/matrix-org/synapse/security/advisories/GHSA-3x4c-pq33-4w3qThird Party Advisory
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2VHDEPCZ22GJFMZCWA2XZAGPOEV72POF/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PXT7ID7DNBRN2TVTETU3SYQHJKEG6PXN/
- https://github.com/matrix-org/synapse/commit/cb35df940aPatch, Third Party Advisory
- https://github.com/matrix-org/synapse/releases/tag/v1.41.1Release Notes, Third Party Advisory
- https://github.com/matrix-org/synapse/security/advisories/GHSA-3x4c-pq33-4w3qThird Party Advisory
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2VHDEPCZ22GJFMZCWA2XZAGPOEV72POF/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PXT7ID7DNBRN2TVTETU3SYQHJKEG6PXN/
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.