Jenkins Script Security Plugin 1415.v9a_f9b_3a_c253d and earlier does not check the method called through the proxy created when a sandboxed script coerces a value to an interface, if the value inherits a method of the same name as an interface method, allowing attackers with permission to define and run sandboxed scripts, including Pipelines, to bypass the sandbox protection and execute arbitrary code in the context of the Jenkins controller JVM.