CVE-2018-1000866

A sandbox bypass vulnerability exists in Pipeline: Groovy Plugin 2.59 and earlier in groovy-sandbox/src/main/java/org/kohsuke/groovy/sandbox/SandboxTransformer.java, groovy-cps/lib/src/main/java/com/cloudbees/groovy/cps/SandboxCpsTransformer.java that allows attackers with Job/Configure permission, or unauthorized attackers with SCM commit privileges and corresponding pipelines based on Jenkinsfiles set up in Jenkins, to execute arbitrary code on the Jenkins master JVM

Mitigation

Do not run untrusted jenkins pipeline scripts.