The Firelight Lightbox WordPress plugin before 2.3.16 does not sanitise and escape title attributes before outputting them in the page, which could allow users with a role as low as contributors to perform stored Cross-Site Scripting attacks.
The Firelight Lightbox WordPress plugin before 2.3.15 does not prevent users with post writing capabilities from executing arbitrary Javascript when the jQuery Metadata library is enabled. While this feature is meant to only be available to Pro version users, it can be activated in the free version too, making it theoretically exploitable there as well.
Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in FirelightWP Firelight Lightbox allows Stored XSS.This issue affects Firelight Lightbox: from n/a through 2.3.3.