The REST Plugin in Apache Struts 2.1.1 through 2.3.x before 2.3.34 and 2.5.x before 2.5.13 uses an XStreamHandler with an instance of XStream for deserialization without any type filtering, which can lead to Remote Code Execution when deserializing XML payloads.
https://www.kb.cert.org/vuls/id/112992
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170907-struts2
https://struts.apache.org/docs/s2-052.html
https://security.netapp.com/advisory/ntap-20170907-0001/
https://cwiki.apache.org/confluence/display/WW/S2-052
https://bugzilla.redhat.com/show_bug.cgi?id=1488482
https://blogs.apache.org/foundation/entry/apache-struts-statement-on-equifax
http://www.oracle.com/technetwork/security-advisory/alert-cve-2017-9805-3889403.html