This indicates an attack attempt to exploit a remote Code Execution vulnerability in Oracle Java.
The vulnerability is due to an error when the vulnerable software attempts to convert field types in Java. A remote attacker may be able to exploit this to execute arbitrary code within the context of the application, via a crafted Java file.
JDK and JRE 7 Update 17 and earlier
JDK and JRE 6 Update 43 and earlier
JDK and JRE 5.0 Update 41 and earlier
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.