Citrix NetScaler AppFirewall, as used in NetScaler 10.5, allows remote attackers to bypass intended firewall restrictions via a crafted Content-Type header, as demonstrated by the application/octet-stream and text/xml Content-Types.
https://www.exploit-db.com/exploits/36369/
https://euvd.enisa.europa.eu/vulnerability/EUVD-2015-2929