The default whitelist included the following unsafe entries: DefaultGroovyMethods.putAt(Object, String, Object)

DefaultGroovyMethods.getAt(Object, String). These allowed circumventing many of the access restrictions implemented in the script sandbox by using e.g. currentBuild['rawBuild'] rather than currentBuild.rawBuild. Additionally, the following entries allowed accessing private data that would not be accessible otherwise due to script security: groovy.json.JsonOutput.toJson(Closure)

groovy.json.JsonOutput.toJson(Object).