Citrix XenServer Multiple Security Updates

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

• CVE-2017-10920, CVE-2017-10921 and CVE-2017-10922 (High): Grant table operations mishandle reference counts.
• CVE-2017-10918 (High): Stale P2M mappings due to insufficient error checking.
• CVE-2017-10912 (Medium): Page transfer may allow PV guest to elevate privilege.
• CVE-2017-10913 and CVE-2017-10914 (Medium): Races in the grant table unmap code.
• CVE-2017-10915 (Medium): x86: insufficient reference counts during shadow emulation.
• CVE-2017-10917 (Medium): NULL pointer deref in event channel poll.
• CVE-2017-10911 (Low): blkif responses leak backend stack data.

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 7.2: CTX224692 – https://support.citrix.com/article/CTX224692 and CTX224698 – https://support.citrix.com/article/CTX224698

Citrix XenServer 7.1: CTX224691 – https://support.citrix.com/article/CTX224691 and CTX224697 – https://support.citrix.com/article/CTX224697

Citrix XenServer 7.0: CTX224690 – https://support.citrix.com/article/CTX224690 and CTX224696 – https://support.citrix.com/article/CTX224696

Citrix XenServer 6.5 SP1: CTX224689 – https://support.citrix.com/article/CTX224689 and CTX224695 – https://support.citrix.com/article/CTX224695

Customers who have deployed Citrix XenServer 6.2 SP1 on older hardware that does not have Hardware Assisted Paging support (Intel: EPT, AMD: RVI) should upgrade to Citrix XenServer 6.5 SP1 or later to ensure that they are protected against these issues.

Citrix XenServer 6.2 SP1: CTX224688 – https://support.citrix.com/article/CTX224688 and CTX224694 – https://support.citrix.com/article/CTX224694

Citrix XenServer 6.0.2 Common Criteria: CTX224687 – https://support.citrix.com/article/CTX224687 and CTX224693 – https://support.citrix.com/article/CTX224693

Customers who are using the Live Patching feature of Citrix XenServer 7.2 may apply the relevant hotfixes without requiring a reboot.  Customers who are using the Live Patching feature of Citrix XenServer 7.1 who have previously deployed all earlier hotfixes may apply the relevant hotfixes without requiring a reboot.