This indicates an attack attempt against a Command Injection vulnerability in Mako Server.
The vulnerability is due to insufficient sanitizing of user supplied inputs in the application when parsing HTTP requests. A remote attacker may be able to exploit this to execute arbitrary code within the context of the application, via a crafted request.
Mako Server version 2.5
System Compromise: Remote attackers can gain control of vulnerable systems.
We are currently unaware of any vendor supplied patches available for this issue.