WP Inventory Manager <= 2.5.1 - Authenticated (Contributor+) SQL Injection via 'where' Shortcode Attribute

Summary

The WP Inventory Manager plugin for WordPress is vulnerable to SQL Injection via the 'where' shortcode attribute of the [wpinventory] shortcode in versions up to, and including, 2.5.1. This is due to insufficient escaping on the user-supplied parameter and lack of sufficient preparation on the existing SQL query in the WPIMItem::get_all() function — parse_custom_where() only performs html_entity_decode(), strips semicolons, and does field-label name replacements, without using $wpdb->prepare() or a whitelist. The resulting string is concatenated into a raw SELECT statement that is executed via $wpdb->get_results(). This makes it possible for authenticated attackers, with Contributor-level access and above, to append additional SQL queries into already existing queries that can be used to extract sensitive information from the database.