The DHCP client on D-Link DIR-850L REV. A (with firmware through FW114WWb07_h2ab_beta1) and REV. B (with firmware through FW208WWb02) devices allows unauthenticated remote code execution as root because /etc/services/INET/inet_ipv4.php mishandles shell metacharacters, affecting generated files such as WAN-1-udhcpc.sh.