Cross-site scripting (XSS) vulnerability in (1) Text_Filter/Filter/xss.php in Horde 3.1.x before 3.1.9 and 3.2.x before 3.2.2 and (2) externalinput.php in Popoon r22196 and earlier allows remote attackers to inject arbitrary web script or HTML by using / (slash) characters as replacements for spaces in an HTML e-mail message.