Is CVE-2016-9385 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2016-9385 being exploited in the wild.

How severe is CVE-2016-9385?

Medium severity, with a CVSS score of 6, published 23 January 2017.

Which products and versions are affected?

Citrix Xenserver 6.0.2, 6.2.0, 6.5, 7.0; Xen Project Xen 4.4.x through 4.7.x.

Is there a fix for CVE-2016-9385?

A patch was published on 2016-11-22: Patches released for Xen unstable, 4.7.x, 4.6.x, 4.5.x, and 4.4.x Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2016-9385 attacked?

It is attacked with local access, in an operating system.

Am I affected by CVE-2016-9385?

Check whether you run Citrix Xenserver or Xen Project Xen at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2016-9385: Xen x86 segment base write emulation denial of service

CVE-2016-9385 · Severity: medium · CVSS 6 · Published 2017-01-23

Xen is a hypervisor used to run multiple virtual machines on a single physical server. A vulnerability in how it handles certain processor instructions allows an administrator of a guest virtual machine to crash the entire physical host. This results in a total service outage for all other virtual machines running on that same hardware.

Technologies: Citrix Xenserver, Xen Project Xen. Vendors: Citrix, Xen Project.

Quick answers

Is CVE-2016-9385 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2016-9385 being exploited in the wild.
How severe is CVE-2016-9385?: Medium severity, with a CVSS score of 6, published 23 January 2017.
Which products and versions are affected?: Citrix Xenserver 6.0.2, 6.2.0, 6.5, 7.0; Xen Project Xen 4.4.x through 4.7.x.
Is there a fix for CVE-2016-9385?: A patch was published on 2016-11-22: Patches released for Xen unstable, 4.7.x, 4.6.x, 4.5.x, and 4.4.x Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2016-9385 attacked?: It is attacked with local access, in an operating system.
Am I affected by CVE-2016-9385?: Check whether you run Citrix Xenserver or Xen Project Xen at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A vulnerability exists in Xen's emulation of x86 segment base writes, specifically affecting the FS and GS register base MSRs and the WRFSBASE/WRGSBASE instructions. These instructions require input values to be in canonical form; otherwise, a general protection fault (#GP) is triggered. The hypervisor's recovery code for these faults was inadvertently removed when support for these instructions was enabled. A malicious administrator of a Paravirtualized (PV) guest can provide non-canonical addresses to trigger an unhandled #GP fault, leading to a hypervisor crash and host-wide denial of service. HVM guests are not affected. Patches are available from the Xen Project (XSA-193).

Affected products

Xen Project Xen 4.4.x through 4.7.x
Citrix XenServer 6.0.2, 6.2.0, 6.5, 7.0

Timeline

2016-11-22: advisory: XSA-193 public release
2016-11-22: patched: Patches released for Xen unstable, 4.7.x, 4.6.x, 4.5.x, and 4.4.x
2017-01-23: disclosed: NVD publication date

References

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