CVE-2021-39164

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.

• CVE ID
• CVE-2021-39164

• Assigner
• security-advisories@github.com

• Vulnerability Status
• Analyzed

• Published Version
• 2021-08-31T17:15:08

• Last Modified Date
• 2022-10-25T18:04:38

• Version
• 2.0

• Vector String
• AV:N/AC:M/Au:S/C:P/I:N/A:N

• Access Vector
• NETWORK

• Access Compatibility
• MEDIUM

• Authentication
• SINGLE

• Confidentiality Impact
• PARTIAL

• Integrity Impact
• NONE

• Availability Impact
• NONE

• Base Score
• 3.5

• Severity
• LOW

• Exploitability Score
• 6.8

• Impact Score
• 2.9

• Version
• 3.1

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

• Attack Vector
• NETWORK

• Attack Compatibility
• HIGH

• Privileges Required
• LOW

• User Interaction
• NONE

• Scope
• UNCHANGED

• Confidentiality Impact
• LOW

• Availability Impact
• NONE

• Base Score
• 3.1

• Base Severity
• LOW

• Exploitability Score
• 1.6

• Impact Score
• 1.4