Simple Popup Images <= 1.8.6 is vulnerable to Cross Site Scripting (XSS) vulnerability

The Simple Popup Images plugin for WordPress is vulnerable to Stored Cross-Site Scripting via admin settings in versions up to, and including, 1.8.6 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers , with administrator-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This only impacts multi-site installations and installations where unfiltered_html has been disabled.