Description of Problem
A number of vulnerabilities have been found in Citrix Hypervisor (formerly Citrix XenServer) that allow the host to be compromised by:
i. Privileged code in a guest VM that has been assigned a PCI passthrough device
ii. Privileged code in a PV guest VM
iii. Unprivileged code in a 32-bit PV guest VM
These vulnerabilities have the following identifiers:
• CVE-2019-18420
• CVE-2019-18421
• CVE-2019-18424
• CVE-2019-18425
These issues affect all currently supported versions of Citrix Hypervisor up to and including Citrix Hypervisor 8.0.
Mitigating Factors
Customers running only HVM workloads and not making use of PCI passthrough functionality are not affected by these issues. Note that all Microsoft Windows VMs run as HVM VMs.
What Customers Should Do
Hotfixes have been released to address these issues. Citrix recommends that affected customers install these hotfixes as their patching schedules allow. The hotfixes can be downloaded from the following locations:
Citrix Hypervisor 8.0:
CTX262555 - https://support.citrix.com/article/CTX262555
CTX258428 - https://support.citrix.com/article/CTX258428
Citrix XenServer 7.6:
CTX262554 - https://support.citrix.com/article/CTX262554
CTX258425 - https://support.citrix.com/article/CTX258425
Citrix XenServer 7.1 LTSR CU2:
CTX262553 - https://support.citrix.com/article/CTX262553
CTX258424 - https://support.citrix.com/article/CTX258424
Citrix XenServer 7.0:
CTX258417 - https://support.citrix.com/article/CTX258417
CTX258423 - https://support.citrix.com/article/CTX258423
What Citrix Is Doing
Citrix is notifying customers and channel partners about this potential security issue. This article is also available from the Citrix Knowledge Center at http://support.citrix.com/.
Obtaining Support on This Issue
If you require technical assistance with this issue, please contact Citrix Technical Support. Contact details for Citrix Technical Support are available at https://www.citrix.com/support/open-a-support-case.html.
Reporting Security Vulnerabilities
Citrix welcomes input regarding the security of its products and considers any and all potential vulnerabilities seriously. For guidance on how to report security-related issues to Citrix, please see the following document: CTX081743 – Reporting Security Issues to Citrix
Changelog
| Date | Change |
| 31st October 2019 | Initial publication |