Concrete CMS: Unauthenticated reflected XSS in preview_as_user function

An unauthenticated, reflected cross-site-scripting attack is possible due to the unsanitised cID parameter in the previewasuser functionality. Example URL: https://LOCAL-CONCRETE-INSTALL/ccm/system/panels/page/previewasuser/preview?cID=%22%3E%3C/iframe%3E%3Cscript%3Ealert1%3C/script%3E%3C!-- The...