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                             CERT-Renater

                 Note d'Information No. 2018/VULN111
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DATE                : 22/03/2018

HARDWARE PLATFORM(S): /

OPERATING SYSTEM(S): Systems running Citrix XenServer versions 7.x
                                      prior to 7.4.

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https://support.citrix.com/article/CTX232655
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Citrix XenServer Multiple Security Updates

Security Bulletin | Critical
| Created: 21 Mar 2018 | Modified: 21 Mar 2018

Applicable Products

  o XenServer 7.3
  o XenServer 7.2
  o XenServer 7.1 LTSR Cumulative Update 1
  o XenServer 7.0

Description of Problem

A number of vulnerabilities have been identified within Citrix
XenServer that could, if exploited, allow a malicious administrator of
a guest VM to crash the host and, for some XenServer versions, allow a
remote attacker to compromise the host.

The following vulnerabilities have been addressed:

  o CVE-2016-2074: openvswitch: MPLS buffer overflow vulnerability
  o CVE-2018-7540: DoS via non-preemptable L3/L4 pagetable freeing
  o CVE-2018-7541: grant table v2 -> v1 transition may crash Xen

The host compromise issue (CVE-2016-2074) affects Citrix XenServer
versions 7.0 and 7.1 CU1 only.
The denial of service issues affect all supported versions of Citrix
XenServer prior to version 7.4.


Mitigating Factors

Customers using the "Linux bridge" networking mode are unaffected by
the host compromise issue.


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 7.3: CTX233368 -
https://support.citrix.com/article/CTX233368

Citrix XenServer 7.2: CTX233366 -
https://support.citrix.com/article/CTX233366

Citrix XenServer 7.1 LTSR CU1: CTX233363 -
https://support.citrix.com/article/
CTX233363 and CTX233365 - https://support.citrix.com/article/CTX233365

Citrix XenServer 7.0: CTX233362 -
https://support.citrix.com/article/CTX233362
and CTX233364 - https://support.citrix.com/article/CTX233364

These hotfixes are not livepatchable.

Citrix is actively working on remediating the denial of service issues
for releases that are End of Maintenance but not yet End of Life.


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                             |
+----------------------------------+------------------------------------------+
|21st March 2018                   |Initial publication                |
+----------------------------------+------------------------------------------+


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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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