Citrix NetScaler Application Delivery Controller (ADC) and NetScaler Gateway 10.5 before build 67.13, 11.0 before build 71.22, 11.1 before build 56.19, and 12.0 before build 53.22 allow remote attackers to obtain sensitive information from the backend client TLS handshake by leveraging use of TLS with Client Certificates and a Diffie-Hellman Ephemeral (DHE) key exchange.