Microsoft has published temporary workarounds for a serious Citrix gateway vulnerability that has recently surfaced.  A security patch is being formulated & should be available soon.

https://www.us-cert.gov/ncas/current-activity/2020/01/08/citrix-application-delivery-controller-and-citrix-gateway

https://www.thezdi.com/blog/2020/1/14/the-january-2020-security-update-review

We don’t normally discuss Citrix patches on this blog, but a recent bug (CVE-2019-19781) has been described as “one of the most dangerous bugs disclosed in recent years,” and a proof-of-concept exploit has been made public. What’s worse is that patches are not available yet but are scheduled for later this month. If you use Citrix, you should follow the mitigations posted here and look to apply patches as soon as they become available.