Mattermost Fails to Sanitize Path Traversal Sequences

Mattermost versions 10.8.x = 10.8.3, 10.5.x = 10.5.8, 9.11.x = 9.11.17, 10.9.x = 10.9.2 fails to sanitize path traversal sequences in template file destination paths, which allows a system admin to perform path traversal attacks via malicious path components, potentially enabling malicious file...