The Online Booking & Scheduling Calendar for WordPress by vcita plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the 'wp_id' parameter in all versions up to, and including, 4.4.2 due to missing authorization checks on processAction function, as well as insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts that will execute whenever a user accesses a wp-admin dashboard.