This indicates an attack attempt to exploit a Cross Site Scripting vulnerability in phpMyAdmin.
The vulnerability is due to insufficient sanitizing of user supplied inputs in the application. As a result, a remote attacker can exploit this to store and execute arbitrary script code within the context of the application.
phpMyAdmin Devel Team phpMyAdmin 4.0 through 4.8.3
System Compromise: Remote attackers can execute arbitrary script code in the context of the affected site.
Apply the most recent upgrade or patch from the vendor: