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             AUSCERT External Security Bulletin Redistribution

            Citrix XenServer Security Update for CVE-2018-3665
                               18 June 2018


        AusCERT Security Bulletin Summary

Product:           Citrix XenServer
Publisher:         Citrix
Operating System:  Citrix XenServer
Impact/Access:     Access Privileged Data -- Existing Account
Resolution:        Patch/Upgrade
CVE Names:         CVE-2018-3665  

Reference:         ESB-2018.1770

Original Bulletin: 

- --------------------------BEGIN INCLUDED TEXT--------------------


Citrix XenServer Security Update for CVE-2018-3665

Security Bulletin | High | Created: 15 Jun 2018 | Modified: 15 Jun 2018

Applicable Products

  o XenServer 7.0
  o XenServer 7.1 LTSR Cumulative Update 1
  o XenServer 7.3
  o XenServer 7.4
  o XenServer 7.5

Description of Problem

An issue has been identified in certain CPUs that may allow code running in a
guest VM to read data from another process in the same VM or another VM running
on the same host.  The data that can be read is limited to specific CPU
registers rather than memory or disk storage; however, those registers may
contain sensitive information.

This issue affects all currently supported versions of Citrix XenServer up to
and including Citrix XenServer 7.5.

The following issue has been addressed:

  o CVE-2018-3665: Speculative register leakage from lazy FPU context switching

Mitigating Factors

Customers with AMD-based CPUs are believed to be unaffected by this issue.

What Customers Should Do

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

Citrix XenServer 7.5: CTX235135 - https://support.citrix.com/article/CTX235135

Citrix XenServer 7.4: CTX235175 - https://support.citrix.com/article/CTX235175

Citrix XenServer 7.3: CTX235956 - https://support.citrix.com/article/CTX235956

Citrix XenServer 7.1 LTSR CU1: CTX235957 - https://support.citrix.com/article/

Citrix XenServer 7.0: CTX235958 - https://support.citrix.com/article/CTX235958

Citrix recommends that customers follow the guidance of their operating system
vendors for updates to the operating systems of their guest VMs.

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  https://www.citrix.com/support/open-a-support-case.html. 

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

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