Script Security Plugin did not apply sandboxing restrictions to constructor invocations via positional arguments list, super constructor invocations, method references, and type coercion expressions. This could be used to invoke arbitrary constructors and methods, bypassing sandbox protection.

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).

The Script Security plugin before 1.18.1 in Jenkins might allow remote attackers to bypass a Groovy sandbox protection mechanism via a plugin that performs (1) direct field access or (2) get/set array operations.