Multiple cross-site scripting (XSS) vulnerabilities in the MailChimp module 7.x-2.x before 7.x-2.7 for Drupal allow remote attackers to inject arbitrary web script or HTML via vectors related to (1) a predictable "webhook URL key" and (2) improper sanitization of "Webhook variables from POST requests."
http://www.securityfocus.com/bid/56234
http://www.openwall.com/lists/oss-security/2012/11/20/4