This indicates a possible attack against a Command Execution vulnerability in Apache Roller.
The vulnerability is due to insufficient sanitizing of user supplied inputs in the application. A remote attacker may exploit this by sending a specially crafted HTTP request to a vulnerable system. A successful attack may allow an attacker to execute arbitrary OGNL expressions in the security context of the web application server.
Apache Software Foundation Apache Roller prior to 5.0.2
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.