This indicates a possible attack against a Command Injection vulnerability in Linksys WRT54GL.
The vulnerability is due to insufficient sanitizing of user supplied inputs in the application when parsing HTTP requests. A remote attacker may be able to exploit this to execute arbitrary code within the context of the application, via a crafted HTTP request.
Linksys WRT54GL 1.1 Firmware-Version 4.30.15 build 2
System Compromise: Remote attackers can execute arbitrary code on vulnerable systems.
Upgrade WRT54GL to the latest firmware version.