CVE-2026-4055

Mattermost versions 11.5.x = 11.5.1 fail to validate team-level runcreate permission against the target team when creating a playbook run which allows an authenticated team member to create runs in teams where they lack permission via specifying a different team ID in the run creation API request...

CVE-2026-4055

Mattermost versions 11.5.x = 11.5.1 fail to validate team-level runcreate permission against the target team when creating a playbook run which allows an authenticated team member to create runs in teams where they lack permission via specifying a different team ID in the run creation API request...

CVE-2026-4055 Insufficient permission validation on cross-team playbook run creation

Mattermost versions 11.5.x = 11.5.1 fail to validate team-level runcreate permission against the target team when creating a playbook run which allows an authenticated team member to create runs in teams where they lack permission via specifying a different team ID in the run creation API request...

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...