Jenkins Script Security Plugin 1415.v9a_f9b_3a_c253d and earlier checks the operations Groovy will perform with the elements it reads from a collection that a sandboxed script casts to another type but performs the cast on the collection itself, 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.

Jenkins Script Security Plugin 1415.v9a_f9b_3a_c253d and earlier checks the operations Groovy will perform with the elements it reads from a collection that a sandboxed script casts to another type but performs the cast on the collection itself, 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.