WP Ticket <= 6.0.4 - Unauthenticated SQL Injection via WordPress Search 's' Parameter

The WP Ticket plugin for WordPress is vulnerable to SQL Injection via the WordPress search query parameter (`s`) in versions up to, and including, 6.0.4 The plugin hooks WordPress's `posts_request` filter with `wp_ticket_com_posts_request()`, which calls `emd_author_search_results()` when the current request is an unauthenticated front-end search. That function reads `$query->query_vars['s']` — already wp_unslash()'d by `WP_Query::parse_query()`, so wp_magic_quotes protection has been stripped — and concatenates the raw value into a SQL `LIKE` clause inside a UNION sub-SELECT appended to the main query, with no `$wpdb->prepare()` or escaping. This makes it possible for unauthenticated attackers to append additional SQL queries into already-existing queries that can be used to extract sensitive information from the database.