Jenkins Assembla merge request builder Plugin missing authentication to access endpoint

Jenkins Assembla merge request builder Plugin provides a webhook endpoint at /assembla-webhook/ that can be used to trigger builds of jobs configured to use a specified repository.

In Assembla merge request builder Plugin 1.1.13 and earlier, this endpoint can be accessed without authentication. This allows unauthenticated attackers to trigger builds of jobs corresponding to the attacker-specified repository.