Buffer overflow in Broadcom ACSD allows remote attackers to execute arbitrary code via a long string to TCP port 5916. This component is used on routers of multiple vendors including ASUS RT-AC66U and TRENDnet TEW-812DRU.
https://packetstormsecurity.com/files/122562/ASUS-RT-AC66U-ACSD-Remote-Root-Buffer-Overflow.html
https://euvd.enisa.europa.eu/vulnerability/EUVD-2013-4514
http://www.linux-magazine.com/Issues/2014/161/Security-and-SOHO-Routers