The PING function on the TP-Link TL-WR840N EU v5 router with firmware through TL-WR840N(EU)_V5_171211 is vulnerable to remote code execution via a crafted payload in an IP address input field.
The traceroute function on the TP-Link TL-WR840N v4 router with firmware through 0.9.1 3.16 is vulnerable to remote code execution via a crafted payload in an IP address input field.