The Jenkins CLI subsystem in Jenkins before 1.638 and LTS before 1.625.2 allows remote attackers to execute arbitrary code via a crafted serialized Java object, related to a problematic webapps/ROOT/WEB-INF/lib/commons-collections-*.jar file and the "Groovy variant in 'ysoserial'".
https://wiki.jenkins-ci.org/display/SECURITY/Jenkins+Security+Advisory+2015-11-11
https://access.redhat.com/errata/RHSA-2016:0070
http://www.openwall.com/lists/oss-security/2015/11/18/2
http://www.openwall.com/lists/oss-security/2015/11/18/13
http://www.openwall.com/lists/oss-security/2015/11/18/11