WordPress appointment-booking-calendar 1.1.24 contains multiple privilege escalation vulnerabilities that allow unauthenticated attackers to modify calendar settings and inject persistent cross-site scripting payloads through the admin.php page parameters. Attackers can inject malicious JavaScript into the 'ict' and 'ics' options or the calendar 'name' parameter via GET requests to execute arbitrary scripts when the calendar is displayed or accessed in the administration interface.