ASUS RT-AC68U RT-AC66R RT-AC66U RT-AC56R RT-AC56U RT-N66R RT-N66U RT-N56R RT-N56U and possibly other RT-series routers before firmware 3.0.0.4.376.x do not verify the integrity of firmware (1) update information or (2) downloaded updates which allows man-in-the-middle (MITM) attackers to execute arbitrary code via a crafted image.