Prodder before 0.5, and perlpodder before 0.5, allows remote attackers to execute arbitrary code via shell metacharacters in the URL of a podcast (url attribute of an enclosure tag, or $enc_url variable), which is executed when running wget.
https://exchange.xforce.ibmcloud.com/vulnerabilities/26575
https://exchange.xforce.ibmcloud.com/vulnerabilities/26568
http://www.vupen.com/english/advisories/2006/1905
http://www.securityfocus.com/archive/1/434712/100/0/threaded
http://sourceforge.net/project/shownotes.php?release_id=418189&group_id=148643
http://securityreason.com/securityalert/942
http://secunia.com/advisories/20238
http://secunia.com/advisories/20208
http://archives.neohapsis.com/archives/fulldisclosure/2006-05/0567.html