procmail in Ingo H3 before 1.1.2 Horde module allows remote authenticated users to execute arbitrary commands via shell metacharacters in the mailbox destination of a filter rule.
http://www.vupen.com/english/advisories/2006/4124
http://www.securityfocus.com/bid/20637
http://www.gentoo.org/security/en/glsa/glsa-200611-22.xml
http://www.debian.org/security/2006/dsa-1204
http://secunia.com/advisories/23100
http://secunia.com/advisories/22656
http://secunia.com/advisories/22482
http://lists.horde.org/archives/announce/2006/000296.html
http://bugs.horde.org/ticket/?Horde=6ed1a009f3396864553976a45948339e&id=4513