How exploitable is this really? First, the machine has to do a PXE boot. In almost EVERY machine I have set up, it boots from fixed media first. Second, you have for force a machine reboot, and the machine has to be on a network you can reach.
Sure, there are lots of machines that PXE boot, but if it's on a public facing machine, why would you even configure it to PXE boot?
Sure, there are lots of machines that PXE boot, but if it's on a public facing machine, why would you even configure it to PXE boot?