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             AUSCERT External Security Bulletin Redistribution

                Citrix XenServer Multiple Security Updates
                              13 October 2017


        AusCERT Security Bulletin Summary

Product:           XenServer
Publisher:         Citrix
Operating System:  Windows
                   Network Appliance
Impact/Access:     Root Compromise -- Existing Account
Resolution:        Patch/Upgrade

Original Bulletin: 

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Citrix XenServer Multiple Security Updates

Security Bulletin | High | Created: 12 Oct 2017 | Modified: 12 Oct 2017

Applicable Products

XenServer 7.2XenServer 7.1 LTSR Cumulative Update 1XenServer 7.1XenServer 
7.0XenServer 6.5XenServer 6.2.0XenServer 6.0.2

Description of Problem

A number of security vulnerabilities have been identified in Citrix
XenServer that may allow a malicious administrator of a guest VM to
compromise the host.

These vulnerabilities affect all currently supported versions of
Citrix XenServer up to and including Citrix XenServer 7.2.

The following vulnerabilities have been addressed:
CVE-2017-TBA0: Unlimited recursion in linear pagetable
CVE-2017-TBA1: Stale TLB entry due to page type
release race 
CVE-2017-TBA2: page type reference leak on x86 
CVE-2017-TBA3: x86: Incorrect handling of self-linear shadow mappings with 
translated guests 
CVE-2017-TBA4: x86: Incorrect handling of IST settings during CPU hotplug
CVE-2017-TBA7: multiple MSI mapping issues on x86
CVE-2017-TBA9: hypervisor stack leak in x86 I/O intercept code 

For customers that do not have PV-based guests, are not using PCI
passthrough and are using hardware with HAP support, the risk is
reduced to a disclosure of a small part of the hypervisor stack.

What Customers Should Do

Hotfixes have been released to address these issues. Citrix strongly
recommends that affected customers install these hotfixes as soon as
possible. The hotfixes can be downloaded from the following locations:

Citrix XenServer 7.2: CTX228722  https://support.citrix.com/article/CTX228722 
Citrix XenServer 7.1 LTSR CU1: CTX228721  https://support.citrix.com/article/CTX228721 
Citrix XenServer 7.1 LTSR: CTX228720  https://support.citrix.com/article/CTX228720 
Citrix XenServer 7.0: CTX228719  https://support.citrix.com/article/CTX228719 
Citrix XenServer 6.5 SP1: CTX228718  https://support.citrix.com/article/CTX228718 
Citrix XenServer 6.2 SP1: CTX228717  https://support.citrix.com/article/CTX228717 
Citrix XenServer 6.0.2 Common Criteria: CTX228716  https://support.citrix.com/article/CTX228716

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 

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 

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


12th October 2017
Initial publishing

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