This indicates an attack attempt to exploit a Denial of Service vulnerability in TFTP Server TFTPDWIN.
The vulnerability is a result of the application's failure to properly sanitize user supplied inputs. A remote attack can exploit this to cause a Denial of Service condition.
ProSysInfo TFTP Server TFTPDWIN 0.4.2 and earlier versions.
Denial of Service: Remote attackers can crash vulnerable systems.
Currently we are not aware of any vendor supplied patch for this issue, and the product has been discontinued.