Multiple cross-site scripting (XSS) vulnerabilities in Horde IMP before 5.0.18 and Horde Groupware Webmail Edition before 4.0.6 allow remote attackers to inject arbitrary web script or HTML via the (1) composeCache, (2) rtemode, or (3) filename_* parameters to the compose page; (4) formname parameter to the contacts popup window; or (5) IMAP mailbox names.  NOTE: some of these details are obtained from third party information.