This indicates an attack attempt to exploit an Insecure Deserialization Vulnerability in Oracle WebLogic Server.
This vulnerability is due to insufficient validation of IIOP requests. A remote unauthenticated attacker can exploit this vulnerability by sending crafted requests to a vulnerable server. Successful exploitation can result in result in arbitrary code execution under the security context of the affected server.
Oracle WebLogic Server 10.3.6
Oracle WebLogic Server 12.1.3
Oracle WebLogic Server 126.96.36.199
Oracle WebLogic Server 188.8.131.52
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.