tplmap (SSTI)

python tplmap.py -u "<url>?name=*"

Tool for detecting and exploiting Server-Side Template Injection (SSTI) in engines such as Jinja2, Twig, Freemarker.

When you suspect a parameter is processed by a template engine (e.g., name, message, template). tplmap tests multiple payloads to detect the engine and then allows executing commands, reading files, etc. It is the standard tool for SSTI.

If the engine has strong sandboxing that blocks payloads, or if the input is heavily sanitized. Also, if you only need to detect existence, you can do it manually.