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:
- CVE-2016-2074: openvswitch: MPLS buffer overflow vulnerability
- CVE-2018-7540: DoS via non-preemptable L3/L4 pagetable freeing
- 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 |