source: http://www.securityfocus.com/bid/27141/info

Pragma Systems FortressSSH is prone to a remote denial-of-service vulnerability because it fails to adequately handle certain exceptions when processing overly long user-supplied input.

Attackers can exploit this issue to exhaust the maximum number of connections alotted for servers. Successful attacks will deny access to legitimate users.

FortressSSH 5.0 is vulnerable; other versions may also be affected. 

https://github.com/offensive-security/exploit-database-bin-sploits/raw/master/bin-sploits/30989.zip