Tugtainer is a self-hosted app for automating updates of Docker containers. Versions prior to 1.30.2 are vulnerable to Server-Side Template Injection (SSTI) in the notification template feature. The title_template and body_template fields are rendered using an unsandboxed jinja2.Environment, allowing any authenticated user to execute arbitrary OS commands as root inside the container. Version 1.30.2 fixes the issue.