Cross-site scripting (XSS) vulnerability in index.php in the beamospetition (com_beamospetition) 1.0.12 component for Joomla! allows remote attackers to inject arbitrary web script or HTML via the pet parameter in a sign action.

More... (http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2009-0378)