Description of Problem

Several security issues have been identified that, collectively, may allow privileged code running in a guest VM to cause the host to crash or to become unresponsive.

These issues have the following CVE identifiers:

CVE ID	Description	Vulnerability Type	Pre-conditions
CVE-2021-26930	An attacker with the ability to execute privileged mode code in a guest can perform a denial of service attack against the host	CWE-664: Improper Control of a Resource Through its Lifetime	Administrator access in guest
CVE-2021-26931	An attacker with the ability to execute privileged mode code in a guest can perform a denial of service attack against the host	CWE-664: Improper Control of a Resource Through its Lifetime	Administrator access in guest
CVE-2021-26932	An attacker with the ability to execute privileged mode code in a guest can perform a denial of service attack against the host	CWE-664: Improper Control of a Resource Through its Lifetime	Administrator access in guest

All supported versions of Citrix Hypervisor are affected by these issues.
 

What Customers Should Do

Citrix has released hotfixes to address these issue. 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: CTX294145 – https://support.citrix.com/article/CTX294145
Citrix Hypervisor 7.1 LTSR: CTX294143 – https://support.citrix.com/article/CTX294143
Citrix Hypervisor 7.0: CTX294141 – https://support.citrix.com/article/CTX294141
 

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 http://www.citrix.com/site/ss/supportContacts.asp.
 

Reporting Security Vulnerabilities

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
2021-02-16	Initial Publication