This indicates an attack attempt to exploit a Command Injection vulnerability in Grandstream UCM6200 series devices.
The vulnerability is due to insufficient sanitizing of user supplied inputs. A remote attacker may be able to exploit this to execute arbitrary commands within the context of the application, via a crafted HTTP request.
Versions below 126.96.36.199
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.