This indicates an attack attempt to exploit a Code Injection Vulnerability in WordPress Infusionsoft Gravity Forms plugin.
The vulnerability is due to an insufficient input validation error when the vulnerable module handles a crafted HTTP request. A remote attacker could exploit this to execute arbitrary code within the context of target application, via a crafted HTTP request.
WordPress Infusionsoft Gravity Forms plugin versions 1.5.3 to 1.5.10
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor