This indicates an attack attempt to exploit a Code Injection vulnerability in CMS Made Simple.
This vulnerability is due to improper validation of the user supplied "code" parameter passed to "editusertag.php". It may allow remote attackers to execute arbitrary code on vulnerable systems, via a craft http request.
CMS Made Simple 2.1.6
System Compromise: Remote attackers can gain control of vulnerable systems.
Currently we are unaware of any vendor supplied patch for this issue.