TP-Link AX1800 WiFi 6 Router (Archer AX21) devices allow unauthenticated attackers (on the LAN) to execute arbitrary code as root via the db_dir field to minidlnad. The attacker obtains the ability to modify files.db, and that can be used to reach a stack-based buffer overflow in minidlna-1.1.2/upnpsoap.c. Exploitation requires that a USB flash drive is connected to the router (customers often do this to make a \\192.168.0.1 share available on their local network).