If you are using Citrix ADC and/or Citrix Gateway, it is better to check your system if any vulnerability exists.
It is a system that optimizes performance of services and applications using some compression and cahing methods.
It is an infrastructure that creates one url for accessing all the applications via different devices remotely in a secure way.
There is an issue reported in access control of Citrix Gateway and ADC which allows unauthorized access.
Update your Citrix Gateway and ADC to the latest version.