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.