Multiple Vulnerabilities Discovered in Citrix ADC, Gateway and SD-WAN WANOP

by Daniel Ruiz
Senior Solutions Architect

Multiple vulnerabilities have been discovered in Citrix ADC (formerly known as NetScaler) and Citrix Gateway (formerly known as NetScaler Gateway), and Citrix SD-WAN WANOP Edition models 4000-WO, 4100-WO, 5000-WO, and 5100-WO.

Citrix strongly recommends that affected customers install relevant updates as soon as possible.  If exploited could result in the following security issues.


  • CVE-2021-22955 – Unauthenticated denial of service  when appliance(s) are configured as a VPN (Gateway) or AAA virtual server
  • CVE-2021-22956  – Temporary disruption of the Management GUI, Nitro API and RPC communication

Products affected:

  • Citrix ADC and Citrix Gateway 13.0 before 13.0-83.27
  • Citrix ADC and Citrix Gateway 12.1 before 12.1-63.22
  • Citrix ADC and NetScaler Gateway 11.1 before 11.1-65.23
  • Citrix ADC 12.1-FIPS before 12.1-55.257
  • Citrix SD-WAN WANOP Edition 11.4 before 11.4.2
  • Citrix SD-WAN WANOP Edition 10.2 before 10.2.9c


Upgrade firmware to the following versions:

  • Citrix ADC and Citrix Gateway 13.1-4.43 and later releases of 13.1
  • Citrix ADC and Citrix Gateway 13.0-83.27 and later releases of 13.0
  • Citrix ADC and Citrix Gateway 12.1-63.22 and later releases of 12.1
  • Citrix ADC and NetScaler Gateway 11.1-65.23 and later releases of 11.1
  • Citrix ADC 12.1-FIPS 12.1-55.257 and later releases of 12.1-FIPS
  • Citrix SD-WAN WANOP Edition 11.4.2 and later releases of 11.4
  • Citrix SD-WAN WANOP Edition 10.2.9c and later releases of 10.2

If you would like more information or assistance from our industry leading team of Citrix experts to plan and execute the upgrade, please contact us at