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                              CERT-Renater

                 Note d'Information No. 2017/VULN138
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DATE                : 04/05/2017

HARDWARE PLATFORM(S): /

OPERATING SYSTEM(S): Systems running XenServer versions 7.1, 7.0,
                                    6.5, 6.2.0, 6.0.2.

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https://support.citrix.com/article/CTX223291
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CTX223291

Citrix XenServer Multiple Security Updates

Security Bulletin | High | Created: 02 May 2017 | Modified: 02 May 2017


Applicable Products

    XenServer 7.1
    XenServer 7.0
    XenServer 6.5
    XenServer 6.2.0
    XenServer 6.0.2


Description of Problem

A number of security issues have been identified within Citrix
XenServer. These issues could, if exploited, allow a malicious
administrator of a PV guest VM to compromise the host. The issues have
the identifiers:

    CVE-TBA1 (High): x86: 64bit PV guest breakout via pagetable
                     use-after-mode-change
    CVE-TBA2 (High): grant transfer allows PV guest to elevate
                     privileges
    CVE-TBA3 (Low): possible memory corruption via failsafe callback


Mitigating Factors

Customers using only HVM guest VMs are not affected. Note that all
Microsoft Windows VMs are HVM.

To exploit these issues from a 32-bit PV guest VM, collaboration with
the administrator of either an HVM guest VM or a 64-bit PV guest VM on
the same host is required.  Customers using only 32-bit PV VMs are not
affected.


What Customers Should Do

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

Citrix XenServer 7.1: CTX223290 –
https://support.citrix.com/article/CTX223290

Citrix XenServer 7.0: CTX223289 –
https://support.citrix.com/article/CTX223289

Citrix XenServer 6.5 SP1: CTX223288 –
https://support.citrix.com/article/CTX223288

Citrix XenServer 6.2 SP1: CTX223287 –
https://support.citrix.com/article/CTX223287

Citrix XenServer 6.0.2 Common Criteria: CTX223286–
https://support.citrix.com/article/CTX223286

Customers who are using the Live Patching feature of Citrix XenServer
7.1 may apply the relevant hotfix without requiring a reboot.


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


Changelog

Date            Change
2nd May 2017 	Initial Publishing

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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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