Home/CVE/Matrix is an ecosystem for open federated Instant Messaging and Voice over IP. In versions 1.41.0 and prior, unauthorise
CVE

CVE-2021-39164

Matrix is an ecosystem for open federated Instant Messaging and Voice over IP. In versions 1.41.0 and prior, unauthorise

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.

LOW · CVSS 3.1 EPSS 0.00271
Monitor
  • No active-exploitation, high-EPSS, or public-exploit signals - routine patching cadence
Sigma rules0 YARA rules0
⬡

Weakness Classification

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

Affected Products & Versions

2
matrix synapse< 1.41.1
fedoraproject fedoraall versions
▤

Affected Packages

1
Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
PyPI matrix-synapse LOW fixed in 1.41.1
▣

Scoring & Timeline

3.1
LOW · CVSS v3.1 · security-advisories@github.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD31 Aug 2021 · 05:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
⚑

Vendor Advisories

1
suse-csafopenSUSE-SU-2024:11041-1
🔗

References & Sources

5
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://github.com/matrix-org/synapse/commit/cb35df940aPatchThird Party Advisory
https://github.com/matrix-org/synapse/releases/tag/v1.41.1Release NotesThird 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/
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