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CVE-2021-39164— Improper authorisation of /members discloses room membership to non-members

Quick assessment

Affected
matrix-org synapse
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Matrix是一个雄心勃勃的新生态系统，用于开放联合即时消息和 VoIP。 Matrix 存在信息泄露漏洞，该漏洞源于产品未对访问用户权限做有效验证。攻击者可通过别的房间的ID来访问成员的敏感信息。以下产品及版本受到影响：1.41.0 及之前版本。

CVSS 3.1 · Low EPSS 1.45% · P73

Possible ATT&CK Techniques 1 AI

T1530 · Data from Cloud Storage
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I. Basic Information for CVE-2021-39164

Vulnerability Information
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Vulnerability Title
Improper authorisation of /members discloses room membership to non-members
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
信息暴露
Source: CVE Program / CVE List V5
Vulnerability Title
Matrix 信息泄露漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Matrix是一个雄心勃勃的新生态系统，用于开放联合即时消息和 VoIP。 Matrix 存在信息泄露漏洞，该漏洞源于产品未对访问用户权限做有效验证。攻击者可通过别的房间的ID来访问成员的敏感信息。以下产品及版本受到影响：1.41.0 及之前版本。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
matrix-org synapse < 1.41.1 -

II. Public POCs for CVE-2021-39164

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III. Intelligence Information for CVE-2021-39164

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Patches & Fixes for CVE-2021-39164 (1)

Vendor Advisories for CVE-2021-39164 (1)

Mailing List Discussions for CVE-2021-39164 (2)

Other References for CVE-2021-39164 (1)

IV. Related Vulnerabilities

Same product: synapse
Same vendor: matrix-org
Same weakness: CWE-200

V. Comments for CVE-2021-39164

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