Pragma FortressSSH 5.0 Build 4 Revision 293 and earlier handles long input to sshd.exe by creating an error-message window and waiting for the administrator to click in this window before terminating the sshd.exe process, which allows remote attackers to cause a denial of service (connection slot exhaustion) via a flood of SSH connections with long data objects, as demonstrated by (1) a long list of keys and (2) a long username.
https://exchange.xforce.ibmcloud.com/vulnerabilities/39354
http://www.securityfocus.com/bid/27141
http://marc.info/?l=bugtraq&m=119947184730448&w=2