Xen 4.6.x and earlier does not properly enforce limits on page order inputs for the (1) XENMEMincreasereservation, (2) XENMEMpopulatephysmap, (3) XENMEMexchange, and possibly other HYPERVISORmemory_op suboperations, which allows ARM guest OS administrators to cause a denial of service (CPU consumption, guest reboot, or watchdog timeout and host reboot) and possibly have unspecified other impact via unknown vectors.