This indicates an attack attempt to exploit a Command Injection vulnerability in IPFire Firewall.
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.
IPFire Team IPFire prior to 2.21 Core Update 124
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor: