source: http://www.securityfocus.com/bid/33169/info

IBM WebSphere DataPower XML Security Gateway XS40 is prone to a remote denial-of-service vulnerability because it fails to handle user-supplied input.

Remote attackers can exploit this issue to cause the device to reboot, denying service to legitimate users.

WebSphere DataPower XML Security Gateway XS40 with firmware 3.6.1.5 is affected; other versions may also be vulnerable. 

The following string is sufficient to trigger this issue:

?abc?