WooCommerce Payments <= 5.9.0 - Authenticated (Shop manager+) SQL Injection via currency parameters

The WooCommerce Payments plugin for WordPress is vulnerable to SQL Injection via the ‘currency', 'currency_is', and 'currency_is_not' parameters in versions up to, and including, 5.9.0 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 shop manager-level access and above, to append additional SQL queries into already existing queries that can be used to extract sensitive information from the database.