Horde 3.3.12, Horde Groupware 1.2.10, and Horde Groupware Webmail Edition 1.2.10, as distributed by FTP between November 2011 and February 2012, contains an externally introduced modification (Trojan Horse) in templates/javascript/open_calendar.js, which allows remote attackers to execute arbitrary PHP code.
https://euvd.enisa.europa.eu/vulnerability/EUVD-2012-0247
https://bugzilla.redhat.com/show_bug.cgi?id=790877
http://packetstormsecurity.org/files/109874/Horde-3.3.12-Backdoor-Arbitrary-PHP-Code-Execution.html
http://lists.horde.org/archives/announce/2012/000751.html
http://eromang.zataz.com/2012/02/15/cve-2012-0209-horde-backdoor-analysis/
http://dev.horde.org/h/jonah/stories/view.php?channel_id=1&id=155