GHSA-q5wx-m95r-4cgc: Comcrete CMS Stored Cross-site Scripting vulnerability

Concrete CMS versions 9.0.0 to 9.3.2 and below 8.5.18 are vulnerable to Stored XSS in RSS Displayer when user input is stored and later embedded into responses. A rogue administrator could inject malicious code into fields due to insufficient input validation.