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                             CERT-Renater

                 Note d'Information No. 2018/VULN215
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DATE                : 29/06/2018

HARDWARE PLATFORM(S): /

OPERATING SYSTEM(S): Systems running Citrix XenServer versions 7.5, 7.4,
                                    7.3, 7.1, 7.0.

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https://support.citrix.com/article/CTX235748
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CTX235748

Citrix XenServer Multiple Security Updates

Security Bulletin | Priority: High
Created: 28 Jun 2018 | Modified: 28 Jun 2018

Applicable Products

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


Description of Problem

Two issues have been identified within Citrix XenServer, which could, if
exploited, allow unprivileged code in a PV guest VM to cause the host to
crash or become unresponsive.

These vulnerabilities affect all currently supported versions of Citrix
XenServer up to and including Citrix XenServer 7.5.

The following vulnerabilities have been addressed:

  * CVE-2018-12893: (High) x86: #DB exception safety check can be
triggered by a guest
  * CVE-2018-12891: (Medium) preemption checks bypassed in x86 PV MM
handling

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What Customers Should Do

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

  * Citrix XenServer 7.5: CTX236153 ?
https://support.citrix.com/article/CTX236153
  * Citrix XenServer 7.4: CTX236152 ?
https://support.citrix.com/article/CTX236152
  * Citrix XenServer 7.3: CTX236151 ?
https://support.citrix.com/article/CTX236151
  * Citrix XenServer 7.1 LTSR CU1: CTX236150 ?
https://support.citrix.com/article/CTX236150
  * Citrix XenServer 7.0: CTX236149 ?
https://support.citrix.com/article/CTX236149

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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/.

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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.

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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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Changelog

+-----------------------------------------------------------------------------+
|Date                  |Change
     |
|----------------------+------------------------------------------------------|
|28th June 2018        |Initial issue
     |
|----------------------+------------------------------------------------------|
|28th June 2018        |Typo - Mark bulletin as High severity
     |
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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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