Citrix ADC and Citrix/NetScaler Gateway before 13.0-82.41, 12.1-62.23, 11.1-65.20 and Citrix ADC 12.1-FIPS before 12.1-55.238 suffer from improper access control allowing SAML authentication hijack through a phishing attack to steal a valid user session. Note that Citrix ADC or Citrix Gateway must be configured as a SAML SP or a SAML IdP for this to be possible.