This indicates an attack attempt to exploit a Command Execution vulnerability in multiple routers.
The vulnerability is due to insufficient sanitizing of user supplied inputs in the application when handling a crafted HTTP request. A remote attacker may be able to exploit this to execute arbitrary code within the context of the application, via a crafted HTTP request.
Sapido multiple routers
Edimax EW-7438RPn 1.13
Bellini/Supercook Wi-Fi Yumi SC200
TOTOLINK multiple routers
System Compromise: Remote attackers can execute arbitrary code on vulnerable systems.
Apply the most recent upgrade or patch from the individual vendors.