A sandbox bypass vulnerability exists in Script Security Plugin 1.47 and earlier in groovy-sandbox/src/main/java/org/kohsuke/groovy/sandbox/SandboxTransformer.java that allows attackers with Job/Configure permission to execute arbitrary code on the Jenkins master JVM, if plugins using the Groovy sandbox are installed.
In Jenkins Script Security Plugin version 1.36 and earlier, users with the ability to configure sandboxed Groovy scripts are able to use a type coercion feature in Groovy to create new `File` objects from strings. This allowed reading arbitrary files on the Jenkins master file system. Such a type coercion is now subject to sandbox protection and considered to be a call to the `new File(String)` constructor for the purpose of in-process script approval.
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.