Concrete CMS version 9 before 9.2.8 and previous versions prior to 8.5.16 is vulnerable to Stored XSS on the calendar color settings screen since Information input by the user is output without escaping. A rogue administrator could inject malicious javascript into the Calendar Color Settings screen which might be executed when users visit the affected page. The Concrete CMS security team gave this vulnerability a CVSS v3.1 score of 2.0 with a vector of AV:N/AC:H/PR:H/UI:R/S:U/C:L/I:N/A:N&version=3.1 https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator   Thank you Rikuto Tauchi for reporting