The REST Plugin in Apache Struts 2.1.2 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.An attacker could use this flaw to execute arbitrary code or conduct further attacks.
Impact:
A RCE attack is possible when using the Struts REST plugin with XStream handler to deserialise XML requests.