On TP-Link TL-WR849N 0.9.1 4.16 devices, a remote command execution vulnerability in the diagnostics area can be exploited when an attacker sends specific shell metacharacters to the panel's traceroute feature.
https://github.com/ElberTavares/routers-exploit/tree/master/tp-link
https://fireshellsecurity.team/hack-n-routers/
http://packetstormsecurity.com/files/156584/TP-Link-TL-WR849N-Remote-Code-Execution.html