WordPress Spider Calendar plugin through 1.4.9 is susceptible to SQL injection. An attacker can execute arbitrary SQL commands via the cat_id parameter in a spiderbigcalendar_month action to wp-admin/admin-ajax.php, thus making it possible to obtain sensitive information, modify data, and/or execute unauthorized administrative operations.
View the template here CVE-2015-2196.yaml
References:
https://wordpress.org/plugins/spider-event-calendar/