This indicates an attack attempt to exploit a Format String Overflow vulnerability in ComSndFTP Server.
The vulnerability is due to insufficient sanitizing of user supplied inputs in the application when handling crafted "USER" commands. As a result, a remote attacker can exploit this to execute arbitrary code within the context of the application or possibly cause a denial of service condition.
ComSndFTP 1.3.7 Beta
System Compromise: Remote attackers can gain control of vulnerable systems
Currently we are not aware of any vendor supplied patch for this issue.