CVE-2021-39164 Information

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 Vector

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N

Reference

https://github.com/matrix-org/synapse/security/advisories/GHSA-3x4c-pq33-4w3q https://github.com/matrix-org/synapse/releases/tag/v1.41.1 https://github.com/matrix-org/synapse/commit/cb35df940a https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/PXT7ID7DNBRN2TVTETU3SYQHJKEG6PXN/ https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/2VHDEPCZ22GJFMZCWA2XZAGPOEV72POF/

Attack Complexity

HIGH

Privileges Required

LOW

User Interaction Required

LOW

Scope

NONE

Confidentiality Impact

UNCHANGED

Integrity Impact

LOW

Availability Impact

NONE

Base Score

NONE

Base Severity

3.1