What is CVE-2016-9386?

CVE-2016-9386 is a high-severity vulnerability in Citrix Xenserver, classified under CWE-264. CVSS score: 7.8/10. Published 2017-01-23.

How severe is CVE-2016-9386?

High severity. CVSS v3 base score is 7.8 out of 10.

Vulnerability in Citrix Xenserver

CVE-2016-9386

The x86 emulator in Xen does not properly treat x86 NULL segments as unusable when accessing memory, which might allow local HVM guest users to gain privileges via vectors involving "unexpected" base/limit values.

Published 2017-01-23 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.004 (36.6th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 37th percentile — 36.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000

Affected products

Citrix Xenserver — versions 6.0.2, 6.2.0, 6.5
Xen

Weakness classification (CWE)

CWE-264

References

www.securityfocus.com/bid/94471 (VDB Entry, Third Party Advisory, vdb-entry)
security.gentoo.org/glsa/201612-56 (vendor-advisory)
support.citrix.com/article/CTX218775 (Patch, Third Party Advisory)
xenbits.xen.org/xsa/advisory-191.html (Patch, Vendor Advisory)
www.securitytracker.com/id/1037340 (VDB Entry, Third Party Advisory, vdb-entry)

Frequently asked questions

What is CVE-2016-9386?: CVE-2016-9386 is a high-severity vulnerability in Citrix Xenserver, classified under CWE-264. CVSS score: 7.8/10. Published 2017-01-23.
How severe is CVE-2016-9386?: High severity. CVSS v3 base score is 7.8 out of 10.