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                             CERT-Renater

                 Note d'Information No. 2021/VULN319
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DATE                : 14/06/2021

HARDWARE PLATFORM(S): /

OPERATING SYSTEM(S): Systems running Citrix Hypervisor.

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https://support.citrix.com/article/CTX316324
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CTX316324
Citrix Hypervisor Security Update

Security Bulletin | Medium | Created: 09 Jun 2021 | Modified: 09 Jun 2021


Applicable Products
    Citrix Hypervisor


Description of Problem

Several security issues have been identified that affect Citrix
Hypervisor:

Two issues, each of which may each allow privileged code in a guest VM
to cause the host to crash or become unresponsive.  These two issues
only affect systems where the malicious guest VM has a physical PCI
device passed through to it by the host administrator.

These issues have the following identifiers:

    CVE-2021-27379
    CVE-2021-28692


A further issue that affects underlying CPU hardware.  Although this is
not an issue in the Citrix Hypervisor product itself, Citrix is
releasing hotfixes that also address this CPU issue.  This issue is of a
type known as “speculative execution attacks” and may allow malicious
code running on a CPU to infer the value of registers or memory
belonging to other processes running on that CPU.


This issue has the following identifiers:

    CVE-2021-0089 (Intel CPUs)/CVE-2021-26313 (AMD CPUs)


  CVE ID	Description	Pre-conditions

CVE-2021-27379	privileged code in a guest VM may cause the host to crash
or become unresponsive	malicious guest VM must have a physical
PCI device passed through by the host administrator and the attacker
must be able to execute privileged code

CVE-2021-28692	privileged code in a guest VM may cause the host to
crash or become unresponsive	malicious guest VM must have a physical
PCI device passed through by the host administrator and the attacker
must be able to execute privileged code

CVE-2021-0089/CVE-2021-26313	malicious code running on a CPU could
infer the value of registers or memory belonging to other processes
running on that CPU	Ability to execute code in a guest VM


Mitigating Factors

Customers who have not assigned a PCI device to a guest VM are not
affected by CVE-2021-27379 or CVE-2021-28692


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: CTX313807 –
https://support.citrix.com/article/CTX313807
Citrix XenServer 7.1 LTSR CU2: CTX313806 –
https://support.citrix.com/article/CTX313806


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.


Changelog

Date            Change
2021-06-09 	Initial Publication


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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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