Citrix Gateway 11.1, 12.0, and 12.1 has an Inconsistent Interpretation of HTTP Requests. NOTE: Citrix disputes the reported behavior as not a security issue. Citrix ADC only caches HTTP/1.1 traffic for performance optimization
https://support.citrix.com/search
http://seclists.org/fulldisclosure/2020/Mar/11
http://packetstormsecurity.com/files/156661/Citrix-Gateway-11.1-12.0-12.1-Cache-Bypass.html