Coalescent Systems freePBX (formerly Asterisk Management Portal) before 2.2.0rc1 allows attackers to execute arbitrary commands via shell metacharacters in (1) CALLERID(name) or (2) CALLERID(number).
http://www.vupen.com/english/advisories/2006/3019
http://www.securityfocus.com/bid/21359
http://www.freepbx.org/trac/changeset/2076
http://sourceforge.net/project/shownotes.php?group_id=121515&release_id=467129