Multiple cross-site scripting (XSS) vulnerabilities in Horde Kronolith Calendar Application H4 before 3.0.18, as used in Horde Groupware Webmail Edition before 4.0.9, allow remote attackers to inject arbitrary web script or HTML via crafted event location parameters in the (1) month, (2) monthlist, or (3) prevmonthlist fields, related to portal blocks.