The MikroTik Router hAP Lite 6.25 has no protection mechanism for unsolicited TCP ACK packets in the case of a fast network connection, which allows remote attackers to cause a denial of service (CPU consumption) by sending many ACK packets. After the attacker stops the exploit, the CPU usage is 100% and the router requires a reboot for normal operation.
https://www.exploit-db.com/exploits/41601/
https://packetstormsecurity.com/files/141449/Mikrotik-Hap-Lite-6.25-Denial-Of-Service.html