Multiple unspecified API endpoints in Jenkins before 1.650 and LTS before 1.642.2 allow remote authenticated users to execute arbitrary code via serialized data in an XML file, related to XStream and groovy.util.Expando.
https://www.exploit-db.com/exploits/43375/
https://www.exploit-db.com/exploits/42394/
https://wiki.jenkins-ci.org/display/SECURITY/Jenkins+Security+Advisory+2016-02-24