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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2021.2086 Citrix Hypervisor Security Update 10 June 2021 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Hypervisor Publisher: Citrix Operating System: Virtualisation Impact/Access: Denial of Service -- Existing Account Access Confidential Data -- Existing Account Resolution: Patch/Upgrade CVE Names: CVE-2021-28692 CVE-2021-27379 CVE-2021-26313 CVE-2021-0089 CVE-2020-15565 Reference: ESB-2021.1314 ESB-2021.1205 ESB-2020.3678 Original Bulletin: https://support.citrix.com/article/CTX316324 - --------------------------BEGIN INCLUDED TEXT-------------------- Citrix Hypervisor Security Update Reference: CTX316324 Category : Medium Created : 09 June 2021 Modified : 09 June 2021 Applicable Products o 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: o CVE-2021-27379 o 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: o CVE-2021-0089 (Intel CPUs)/CVE-2021-26313 (AMD CPUs) +--------------+-----------------------------+--------------------------------+ |CVE ID |Description |Pre-conditions | +--------------+-----------------------------+--------------------------------+ | | |malicious guest VM must have a | | |privileged code in a guest VM|physical PCI device passed | |CVE-2021-27379|may cause the host to crash |through by the host | | |or become unresponsive |administrator and the attacker | | | |must be able to execute | | | |privileged code | +--------------+-----------------------------+--------------------------------+ | | |malicious guest VM must have a | | |privileged code in a guest VM|physical PCI device passed | |CVE-2021-28692|may cause the host to crash |through by the host | | |or become unresponsive |administrator and the attacker | | | |must be able to execute | | | |privileged code | +--------------+-----------------------------+--------------------------------+ | |malicious code running on a | | |CVE-2021-0089/|CPU could infer the value of |Ability to execute code in a | |CVE-2021-26313|registers or memory belonging|guest VM | | |to other processes running on| | | |that CPU | | +--------------+-----------------------------+--------------------------------+ 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 - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. The decision to follow or act on information or advice contained in this security bulletin is the responsibility of each user or organisation, and should be considered in accordance with your organisation's site policies and procedures. AusCERT takes no responsibility for consequences which may arise from following or acting on information or advice contained in this security bulletin. NOTE: This is only the original release of the security bulletin. It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the author's website to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: https://www.auscert.org.au/bulletins/ =========================================================================== Australian Computer Emergency Response Team The University of Queensland Brisbane Qld 4072 Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). 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