A sandbox bypass vulnerability exists in Jenkins Pipeline: Groovy Plugin 2.63 and earlier in pom.xml, src/main/java/org/jenkinsci/plugins/workflow/cps/CpsGroovyShell.java that allows attackers able to control pipeline scripts to execute arbitrary code on the Jenkins master JVM.
https://jenkins.io/security/advisory/2019-03-06/#SECURITY-1336%20%282%29