All TippingPoint appliances with TOS versions 2.2.3.6514 and below suffer from a flaw where a malformed packet can force the appliance to fallback to layer 2 mode. In this mode the appliance forwards all traffic without inspection.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/48555/tippingBypass.txt
Source: https://packetstormsecurity.com/files/48555/tippingBypass.txt.html