Jenkins Buckminster Plugin does not perform a permission check in a method implementing form validation

Jenkins Buckminster Plugin 1.1.1 and earlier does not perform a permission check in a method implementing form validation.

This allows attackers with Overall/Read permission to check for the existence of an attacker-specified file path on the Jenkins controller file system. A sequence of requests can be used to effectively list the Jenkins controller file system.

As of publication of this advisory, there is no fix.