Availability Calendar < 1.2.1 - Authenticated SQL Injection

The plugin does not escape the category attribute from its shortcode before using it in a SQL statement, leading to a SQL Injection issue, which can be exploited by any user able to add shortcode to posts/pages, such as contributor+

PoC

With an account role as low as contributor, put the following in a page/post: [availabilitycalendar category="1) UNION select user(),user(),user(),user(),user(),user(),user() – "]