Spiffy Calendar <= 4.9.1 - Authenticated (Contributor+) SQL Injection

The Spiffy Calendar plugin for WordPress is vulnerable to SQL Injection via the ‘orderby’ parameter among others in versions up to, and including, 4.9.1 due to insufficient escaping on the user supplied parameter and lack of sufficient preparation on the existing SQL query. This makes it possible for authenticated attackers, with contributor-level permissions and above (or subscriber-level permissions, if the 'Event manager role' option is set to 'Subscriber'), to append additional SQL queries into already existing queries that can be used to extract sensitive information from the database.