The Read More & Accordion plugin for WordPress is vulnerable to time-based blind SQL Injection via the 'orderby' parameter in all versions up to, and including, 3.5.7. This is due to the use of esc_sql() without surrounding the value in quotes in an ORDER BY clause inside the getAllDataByLimit() and getAccordionAllDataByLimit() functions in ReadMoreData.php. The user-supplied $_GET['orderby'] value is only processed through esc_attr() (an HTML-escaping function) before being passed to these database functions, where esc_sql() is applied but the value is directly concatenated-unquoted-into the ORDER BY fragment of the SQL query before $wpdb-prepare() is called.

Because esc_sql() only escapes quote characters and backslashes (which are irrelevant in an unquoted ORDER BY context), an attacker can inject arbitrary SQL expressions such as (SELECT SLEEP(5)) or conditional subqueries to perform time-based blind data extraction. This makes it possible for authenticated attackers with administrator-level access or above (or any role explicitly permitted access to the plugin's admin pages via the yrm-user-roles setting) to extract sensitive data from the database, including administrator credential hashes.