This indicates an attack attempt to exploit a Code Injection Vulnerability in Rocket ServerGraph.
The vulnerability is due to an input validation error while parsing a crafted HTTP request. A remote attacker could exploit this to execute arbitrary code within the context of target application, via a crafted HTTP request.
Rocket ServerGraph 1.2 and prior
System Compromise: Remote attackers can gain control of vulnerable systems.
Currently we are unaware of any vendor supplied patch for this issue.