CVE-2021-39164

Improper authorisation of /members discloses room membership to non-members

Severity Score

3.1

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

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.

Matrix es un ecosistema para la Mensajería Instantánea federada abierta y voz sobre IP. En versiones 1.41.0 y anteriores, unos usuarios no autorizados pueden acceder a la membresía (lista de miembros, con sus nombres para mostrar) de una sala si conocen el ID de la misma. La vulnerabilidad es limitada a las salas con visibilidad del historial "shared". Además, el usuario no autorizado debe estar usando una cuenta en un servidor doméstico vulnerable que esté en la sala. Los administradores de servidores deben actualizar a versión 1.41.1 o posterior para recibir el parche. Se presenta una solución disponible. Los administradores de servidores que usan un proxy inverso podrían, con una pérdida de funcionalidad potencialmente inaceptable, bloquear los endpoints: "/_matrix/client/r0/rooms/{room_id}/members" con el parámetro de consulta "at", y "/_matrix/client/unstable/rooms/{room_id}/members" con el parámetro de consulta "at"

*Credits: N/A

Attack Vector

Network

Attack Complexity

High

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

None

Attack Vector

Network

Attack Complexity

Medium

Authentication

Single

Confidentiality

Partial

Integrity

None

Availability

None

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2021-08-16 CVE Reserved
2021-08-31 CVE Published
2023-11-08 EPSS Updated
2024-08-04 CVE Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CWE-200: Exposure of Sensitive Information to an Unauthorized Actor
CWE-863: Incorrect Authorization

CAPEC

References (5)

URL	Tag	Source
https://github.com/matrix-org/synapse/releases/tag/v1.41.1	Release Notes
https://github.com/matrix-org/synapse/security/advisories/GHSA-3x4c-pq33-4w3q	Third Party Advisory

URL	Date	SRC

URL	Date	SRC
https://github.com/matrix-org/synapse/commit/cb35df940a	2023-11-07

URL	Date	SRC
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2VHDEPCZ22GJFMZCWA2XZAGPOEV72POF	2023-11-07
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PXT7ID7DNBRN2TVTETU3SYQHJKEG6PXN	2023-11-07

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Matrix Search vendor "Matrix"		Synapse Search vendor "Matrix" for product "Synapse"				< 1.41.1 Search vendor "Matrix" for product "Synapse" and version " < 1.41.1"		-		Affected
Fedoraproject Search vendor "Fedoraproject"		Fedora Search vendor "Fedoraproject" for product "Fedora"				34 Search vendor "Fedoraproject" for product "Fedora" and version "34"		-		Affected
Fedoraproject Search vendor "Fedoraproject"		Fedora Search vendor "Fedoraproject" for product "Fedora"				35 Search vendor "Fedoraproject" for product "Fedora" and version "35"		-		Affected