The Citrix ICA (Independent Computing Architecture) protocol uses weak encryption (XOR) for user authentication.

CITRIX Metaframe 1.8 logs the Client Address (IP address) that is provided by the client instead of obtaining it from the packet headers, which allows clients to spoof their public IP address, e.g. through Network Address Translation (NAT).

Citrix MetaFrame up to XP 1.0 Feature 1, except when running on Windows Server 2003, installs a registry key with an insecure ACL, which allows remote authenticated users to gain privileges.