Citrix has recently released two bulletins about their Citrix Hypervisor product, formerly XenServer:
The first one, CTX282314, is about multiple security issues identified in Citrix Hypervisor (formerly Citrix XenServer) that may allow privileged code in a guest VM to cause the host to crash or become unresponsive. In addition, unprivileged code in a PV guest VM may cause that guest VM to crash.
This update applies to the following products:
- Citrix Hypervisor
- XenServer 7.1
- XenServer 7.0
The second bulletin, CTX281574, completes the fix for the issues above, but must be applied only to systems running the following versions:
Citrix Hypervisor 8.1Citrix Hypervisor 8.x for CSS
So, if you have hosts running any of the hypervisors listed above, I recommend installing the relevant patches.
Update, October 8, 2020:
In CTX281574, Citrix has just announced that Hotfix XS81E008 (included in CTX281574) is under review because it appears to cause functional problems. So I recommend holding off on installing it.