Mattermost doesn't validate whether users were correctly owned by the correct Connected Workspace

Mattermost versions 10.11.x = 10.11.12 fail to validate whether users were correctly owned by the correct Connected Workspace which allows a malicious remote server connected using the Conntexted Workspaces feature to change the displayed status of local users via the Connected Workspaces API...

CVE-2026-27769 Connected Workspaces: Malicious remote server can manipulate arbitrary user's status

Mattermost versions 10.11.x = 10.11.12 fail to validate whether users were correctly owned by the correct Connected Workspace which allows a malicious remote server connected using the Conntexted Workspaces feature to change the displayed status of local users via the Connected Workspaces API...

PT-2026-33036

Name of the Vulnerable Software and Affected Versions Mattermost versions 10.11.x through 10.11.12 Description Improper validation of user ownership within the Connected Workspaces feature allows a malicious remote server to change the displayed status of local users via the Connected Workspaces...

CVE-2026-27769: Missing Authorization

Mattermost versions 10.11.x = 10.11.12 fail to validate whether users were correctly owned by the correct Connected Workspace which allows a malicious remote server connected using the Conntexted Workspaces feature to change the displayed status of local users via the Connected Workspaces API...