PowerJob's GroovyEvaluator.evaluate endpoint vulnerable to code injection

A security flaw has been discovered in PowerJob 5.1.0/5.1.1/5.1.2. The affected element is the function GroovyEvaluator.evaluate of the file /openApi/addWorkflowNode of the component OpenAPI Endpoint. The manipulation of the argument nodeParams results in code injection. The attack can be executed remotely. The project was informed of the problem early through an issue report but has not responded yet.