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