Mattermost allows unauthorized channel member management through playbook runs

Mattermost versions 10.5.x = 10.5.5, 9.11.x = 9.11.15, 10.8.x = 10.8.0, 10.7.x = 10.7.2, 10.6.x = 10.6.5 fail to properly enforce channel member management permissions in playbook runs, allowing authenticated users without the 'Manage Channel Members' permission to add or remove users from public...