This indicates an attack attempt to exploit a Security Bypass vulnerability in Oracle Java.
The vulnerability is due to insufficient sanitizing of user supplied inputs in the application. A remote attacker may be able to exploit this to execute arbitrary code within the context of the application, via a crafted class or jnlp 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
JavaFX 2.2.7 and earlier
Security Bypass: Remote attackers can bypass security checks of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.