Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in I Thirteen Web Solution Email Subscription Popup allows Stored XSS.This issue affects Email Subscription Popup: from n/a through 1.2.20.
The Email Subscription Popup WordPress plugin before 1.2.20 does not sanitise and escape a parameter before outputting it back in the page, leading to a Reflected Cross-Site Scripting which could be used against high privilege users such as admin