NmService.exe in Ipswitch WhatsUp Professional 2006 allows remote attackers to cause a denial of service (CPU consumption) via crafted requests to Login.asp, possibly involving the (1) "In]" and (2) "b;tnLogIn" parameters, or (3) malformed btnLogIn parameters, possibly involving missing "[" (open bracket) or "[" (closing bracket) characters, as demonstrated by "&btnLogIn=[Log&In]=&" or "&b;tnLogIn=[Log&In]=&" in the URL.  NOTE: due to the lack of diagnosis by the original researcher, the precise nature of the vulnerability is unclear.