The LatePoint – Calendar Booking Plugin for Appointments and Events plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'button_caption' parameter in the [latepoint_resources] shortcode in versions up to and including 5.3.0. This is due to insufficient output escaping when the 'items' parameter is set to 'bundles'. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.