Improper Authorization

github.com/mattermost/mattermost-server is vulnerable to improper authorization. The vulnerability is due to insufficient validation of team membership permissions in the Add Channel Member API, which allows an attacker to exploit the API endpoint to access user metadata and channel membership...

CVE-2025-11777

Mattermost versions 10.11.x = 10.11.3, 10.5.x = 10.5.11 fail to properly validate team membership permissions in the Add Channel Member API which allows users from one team to access user metadata and channel membership information from other teams via the API endpoint...

GHSA-MQCJ-8C2G-H97Q Mattermost Incorrect Authorization vulnerability

Mattermost versions 10.11.x = 10.11.3, 10.5.x = 10.5.11 fail to properly validate team membership permissions in the Add Channel Member API, which allows users from one team to access user metadata and channel membership information from other teams via the API endpoint...

Mattermost Incorrect Authorization vulnerability

Mattermost versions 10.11.x = 10.11.3, 10.5.x = 10.5.11 fail to properly validate team membership permissions in the Add Channel Member API, which allows users from one team to access user metadata and channel membership information from other teams via the API endpoint...

Incorrect Authorization

Overview Affected versions of this package are vulnerable to Incorrect Authorization due to properly validating team membership permissions in the Add Channel Member API. An attacker can obtain unauthorized access to user metadata and channel membership information from other teams by sending...

CVE-2025-1792 Improper Access Control in Mattermost Channel Member API

Mattermost versions 10.7.x = 10.7.0, 10.5.x = 10.5.3, 9.11.x = 9.11.12 fail to properly enforce access controls for guest users accessing channel member information, allowing authenticated guest users to view metadata about members of public channels via the channel members API endpoint...