Citrix Hypervisor Security Update

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.

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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.

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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&gt;

CTX258428 - [https://support.citrix.com/article/CTX258428](< https://support.citrix.com/article/CTX258428&gt;)

Citrix XenServer 7.6:

CTX262554 - <https://support.citrix.com/article/CTX262554&gt;

CTX258425 - <https://support.citrix.com/article/CTX258425&gt;

Citrix XenServer 7.1 LTSR CU2:

CTX262553 - <https://support.citrix.com/article/CTX262553&gt;

CTX258424 - <https://support.citrix.com/article/CTX258424&gt;

Citrix XenServer 7.0:

CTX258417 - <https://support.citrix.com/article/CTX258417&gt;

CTX258423 - <https://support.citrix.com/article/CTX258423&gt;

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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/&gt;_.

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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&gt;_.

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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

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Changelog

Date	Change
31st October 2019	Initial publication

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