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                             CERT-Renater

                 Note d'Information No. 2021/VULN453
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DATE                : 09/09/2021

HARDWARE PLATFORM(S): /

OPERATING SYSTEM(S): Systems running Citrix Hypervisor.

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https://support.citrix.com/article/CTX325319
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CTX325319
Citrix Hypervisor Security Update


Applicable Products

    Citrix Hypervisor


Description of Problem
Several security issues have been discovered in Citrix Hypervisor that,
collectively, may allow privileged code in a guest VM to compromise or
crash the host.


These issues have the following identifiers:

  CVE-ID        Description                Pre-requisites

CVE-2021-28694	Host denial of service	Malicious privileged code
execution in a guest VM running on a host with firmware that declares
ACPI tables which includes memory regions that are identity mapped for
devices that have been explicitly assigned, by the host administrator,
to that guest VM in PCI passthrough mode.

CVE-2021-28697	Host compromise	Malicious privileged code execution in a
guest VM that has two or more vCPUs allocated to it

CVE-2021-28698	Host denial of service	Malicious privileged code
execution in a guest VM

CVE-2021-28699	Host compromise	Malicious privileged code execution in a
guest VM on a host where the host administrator has modified the guest
or host grant table limits

CVE-2021-28701	Host compromise	Malicious privileged code execution in a
guest VM that has two or more vCPUs allocated to it


All currently supported versions of Citrix Hypervisor are affected by
all of these issues with the exception of CVE-2021-28699 which only
affects Citrix Hypervisor 8.2 LTSR.


What Customers Should Do

Citrix has released hotfixes to address these issues. Citrix recommends
that affected customers install these hotfixes as their patching
schedule allows.  The hotfixes can be downloaded from the following
locations:

Citrix Hypervisor 8.2 LTSR: CTX324257 –
https://support.citrix.com/article/CTX324257
Citrix Hypervisor 7.1 LTSR CU2: CTX324256 –
https://support.citrix.com/article/CTX324256


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 https://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/.


Reporting Security Vulnerabilities to Citrix

Citrix welcomes input regarding the security of its products and
considers any and all potential vulnerabilities seriously. For details
on our vulnerability response process and guidance on how to report
security-related issues to Citrix, please see the following webpage:
https://www.citrix.com/about/trust-center/vulnerability-process.html.


Disclaimer

This document is provided on an "as is" basis and does not imply any
kind of guarantee or warranty, including the warranties of
merchantability or fitness for a particular use. Your use of the
information on the document is at your own risk. Citrix reserves the
right to change or update this document at any time.


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+ CERT-RENATER       |    tel : 01-53-94-20-44          +
+ 23/25 Rue Daviel   |    fax : 01-53-94-20-41          +
+ 75013 Paris        |    email:cert@support.renater.fr +
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