services/go.php in Horde Application Framework 3.0.0 through 3.0.10 and 3.1.0 through 3.1.1 does not properly restrict its image proxy capability, which allows remote attackers to perform "Web tunneling" attacks and use the server as a proxy via (1) http, (2) https, and (3) ftp URL in the url parameter, which is requested from the server.
http://www.vupen.com/english/advisories/2006/2694
http://www.securityfocus.com/archive/1/439255/100/0/threaded
http://www.novell.com/linux/security/advisories/2006_19_sr.html
http://www.debian.org/security/2007/dsa-1406
http://securityreason.com/securityalert/1229
http://secunia.com/advisories/27565
http://secunia.com/advisories/21459
http://secunia.com/advisories/20954