Pebble Templates protection mechanism bypass can lead to arbitrary code execution

Pebble Templates 3.1.5 allows attackers to bypass a protection mechanism and implement arbitrary code execution with springbok. NOTE: the vendor disputes this because input to the Pebble templating engine is intended to include arbitrary Java code, and thus either the input should not arrive from an untrusted source, or else the application using the engine should apply restrictions to the input. The engine is not responsible for validating the input.