Moritz Naumann reported: [1] http://seclists.org/fulldisclosure/2010/Sep/82
a deficiency in the way Horde framework sanitized user-provided 'subdir' parameter, when composing final path to the image file. A remote, unauthenticated user could use this flaw to conduct cross-site scripting attacks (execute arbitrary HTML or scripting code) by providing a specially-crafted URL to the running Horde framework instance.
Upstream patch: [2] http://git.horde.org/diff.php/horde/util/iconbrowser.php?rt=horde-git&r1=a978a35c3e95e784253508fd4333d2fbb64830b6&r2=9342addbd2b95f184f230773daa4faf5ef6d65e9
Sample public URL by Moritz to demonstrate the issue: [3] [pathtohorde]/util/iconbrowser.php?subdir=<body onload="alert('XSS')">&app=horde