SQL injection vulnerability in the com_listing component in Barter Sites component 1.3 for Joomla! allows remote attackers to execute arbitrary SQL commands via the category_id parameter to index.php.
http://my.barter-sites.com/index.php?option=com_content&view=article&id=6&Itemid=25
http://docs.joomla.org/Vulnerable_Extensions_List#Barter_Sites_1.3