Is CVE-2016-9381 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2016-9381 being exploited in the wild.

How severe is CVE-2016-9381?

High severity, with a CVSS score of 7.5, published 23 January 2017.

Which products and versions are affected?

Citrix Xenserver 6.0.2, 6.2.0, 6.5, 7.0; Qemu up to and including 2.7.1, 2.8.0-rc0; Xen Project Xen All versions using QEMU for x86 HVM guests.

Is there a fix for CVE-2016-9381?

A patch was published on 2016-12-31: Gentoo released updated packages Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2016-9381 attacked?

It is attacked with local access, in a software library.

Am I affected by CVE-2016-9381?

Check whether you run Citrix Xenserver, Qemu 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-2016-9381: Xen QEMU race condition in shared ring processing

CVE-2016-9381 · Severity: high · CVSS 7.5 · Published 2017-01-23

A vulnerability exists in the QEMU component of the Xen hypervisor, which is used to run virtual machines. A malicious administrator of a guest virtual machine can exploit a timing flaw to break out of their isolated environment and gain control over the host system. This could lead to a total compromise of the host server and all other virtual machines running on it.

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

Quick answers

Is CVE-2016-9381 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2016-9381 being exploited in the wild.
How severe is CVE-2016-9381?: High severity, with a CVSS score of 7.5, published 23 January 2017.
Which products and versions are affected?: Citrix Xenserver 6.0.2, 6.2.0, 6.5, 7.0; Qemu up to and including 2.7.1, 2.8.0-rc0; Xen Project Xen All versions using QEMU for x86 HVM guests.
Is there a fix for CVE-2016-9381?: A patch was published on 2016-12-31: Gentoo released updated packages Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2016-9381 attacked?: It is attacked with local access, in a software library.
Am I affected by CVE-2016-9381?: Check whether you run Citrix Xenserver, Qemu 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 race condition exists in QEMU's handling of shared rings between the emulator and the hypervisor. Due to improper synchronization or compiler optimizations, QEMU may fetch data from these shared rings twice. A malicious guest administrator can modify the data in the shared memory between the first and second fetch, leading to inconsistent state and potential arbitrary code execution within the QEMU process. On systems without stub domains or other deprivileging mechanisms, this allows a guest-to-host escape. The vulnerability specifically affects x86 HVM guests; ARM and PV guests are not impacted. Patches are available for various QEMU and Xen versions (XSA-197).

Affected products

QEMU QEMU up to and including 2.7.1, 2.8.0-rc0
Xen Project Xen All versions using QEMU for x86 HVM guests
Citrix XenServer 6.0.2, 6.2.0, 6.5, 7.0

Timeline

2016-11-22: advisory: Xen Project released XSA-197
2016-12-31: patched: Gentoo released updated packages
2017-01-23: disclosed: NVD publication date

References

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