This indicates an attack attempt to exploit a Buffer Overflow Vulnerability in Shenzhen TVT DVR and OEM.
The vulnerability is due to insufficient sanitizing of user supplied inputs in the application. A remote attacker can exploit this to execute arbitrary code within the context of the application, via a crafted HTTP request.
Shenzhen TVT DVR and OEM with firmware released before February 2018.
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.