This indicates an attack attempt to exploit a Cross-Site Scripting vulnerability in WordPress plugin Photo Gallery by 10Web.
The vulnerability is due to insufficient sanitizing of user supplied inputs in the application. A remote attacker may be able to exploit this to execute arbitrary script code within the context of the target user's browser.
Affected Version - 1.5.45 & below
System Compromise : Remote attackers can execute arbitrary script code within the context of the target user's browser
Upgrade to Photo Gallery by 10Web 1.5.46