This indicates an attack attempt to exploit a Command Injection vulnerability in Linksys ESeries line of routers.
The vulnerability is due to insufficient sanitizing of user supplied inputs in the application. A remote attacker can exploit this to send a crafted query to execute arbitrary commands on a vulnerable server.
Linksys E1200 Firmware Version 2.0.09 Linksys E2500 Firmware Version 3.0.04
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.