struts: RCE attack via REST plugin with XStream handler to deserialise XML requests

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.

Cisco Media Processing Software before 1.2 on Media Experience Engine (MXE) 5600 devices has a default root password, which makes it easier for context-dependent attackers to obtain access via (1) the local console, (2) an SSH session, or (3) a TELNET session, aka Bug ID CSCto77737.