com_categories in Joomla! before 1.0.12 does not validate input, which has unknown impact and remote attack vectors.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2006-6816
http://www.vupen.com/english/advisories/2006/5202
http://www.securityfocus.com/bid/21810
http://www.joomla.org/content/view/2495/78/