What is CVE-2016-9383?

CVE-2016-9383 is a high-severity vulnerability in Citrix Xenserver, classified under Improper Input Validation. CVSS score: 8.8/10. Published 2017-01-23.

How severe is CVE-2016-9383?

High severity. CVSS v3 base score is 8.8 out of 10.

Improper input validation in Citrix Xenserver

CVE-2016-9383

Xen, when running on a 64-bit hypervisor, allows local x86 guest OS users to modify arbitrary memory and consequently obtain sensitive information, cause a denial of service (host crash), or execute arbitrary code on the host by leveraging broken emulation of bit test instructions.

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

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

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.005 (41.1th percentile), scored 2026-09-30.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 41st percentile — 41.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000

Affected products

Citrix Xenserver — versions 6.0.2, 6.2.0, 6.5
Xen

Weakness classification (CWE)

CWE-20 — Improper Input Validation

References

www.securityfocus.com/bid/94474 (VDB Entry, Third Party Advisory, vdb-entry)
security.gentoo.org/glsa/201612-56 (vendor-advisory)
xenbits.xen.org/xsa/advisory-195.html (Patch, Vendor Advisory)
www.securitytracker.com/id/1037346 (VDB Entry, Third Party Advisory, vdb-entry)
support.citrix.com/article/CTX218775 (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2016-9383?: CVE-2016-9383 is a high-severity vulnerability in Citrix Xenserver, classified under Improper Input Validation. CVSS score: 8.8/10. Published 2017-01-23.
How severe is CVE-2016-9383?: High severity. CVSS v3 base score is 8.8 out of 10.