This indicates an attack attempt to exploit an Insecure Deserialization Vulnerability in Cisco Security Manager (CSM).
A remote, unauthenticated attacker can exploit this vulnerability by sending a specially crafted serialized object. Successful exploitation can result in arbitrary code execution.
Cisco Security Manager (CSM) prior to 4.18
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.