This indicates an attack attempt to exploit an Unauthenticated Remote Code Execution Vulnerability in TP-Link-WA850RE TL Wi-Fi Range Extender.
The vulnerability is due to insufficient sanitizing of user supplied inputs in the application. A remote, unauthenticated attacker can exploit this to execute arbitrary code, via a crafted HTTP request.
TP-Link-WA850RE TL Wi-Fi Range Extender with Firmware version TL-WA850RE_V5_180228
System Compromise: Remote attackers can gain control of vulnerable systems.
Currently we are unaware of any vendor supplied patch for this issue.