Concrete CMS before 8.5.14 and 9 before 9.2.3 allows Cross Site Request Forgery (CSRF) via ccm/calendar/dialogs/event/delete/submit. An attacker can force an admin to delete events on the site because the event ID is numeric and sequential.
Concrete CMS (previously concrete5) versions 8.5.12 and below, and 9.0 through 9.1.3 does not have Secure and HTTP only attributes set for ccmPoll cookies.
Concrete CMS (previously concrete5) versions 8.5.12 and below, and versions 9.0 through 9.1.3 is vulnerable to Reflected XSS on the Reply form because msgID was not sanitized.
Concrete CMS (previously concrete5) versions 8.5.12 and below, and 9.0 through 9.1.3 is vulnerable to stored XSS on API Integrations via the name parameter.
Concrete CMS (previously concrete5) before 9.1 is vulnerable to stored XSS in RSS Displayer via the href attribute because the link element input was not sanitized.