This indicates an attack attempt to exploit an Input Validation Error Vulnerability in PHP-Fusion.
The vulnerability is due to improper validation of user input in HTTP requests. A remote authenticated attacker can exploit the vulnerability by sending a crafted request to the vulnerable server. Successful exploitation could result in the execution of script code in the security context of the target user's browser, when the user visits the page.
PHP-Fusion prior to 9.03.60
System Compromise: Remote attackers can execute arbitrary script code in the context of the affected application.
Apply the most recent upgrade or patch from the vendor.