How severe is CVE-2016-9637?

CVE-2016-9637 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over local access with high attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2016-9637 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (28th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-9637?

CVE-2016-9637 primarily affects Citrix Xenserver. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2016-9637?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2016-9637 published?

CVE-2016-9637 was published on 2017-02-17 and last updated on 2026-06-17.

CVE-2016-9637

CVE-2016-9637 is a high-severity vulnerability in Citrix Xenserver with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-264.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 3.7
EPSS exploit prediction: 0% (28th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-264
Affected product: Citrix Xenserver
Published: 2017-02-17
Last modified: 2026-06-17

Description

The (1) ioport_read and (2) ioport_write functions in Xen, when qemu is used as a device model within Xen, might allow local x86 HVM guest OS administrators to gain qemu process privileges via vectors involving an out-of-range ioport access.

Frequently asked questions

What is CVE-2016-9637?: The (1) ioport_read and (2) ioport_write functions in Xen, when qemu is used as a device model within Xen, might allow local x86 HVM guest OS administrators to gain qemu process privileges via vectors involving an out-of-range ioport access.
How severe is CVE-2016-9637?: CVE-2016-9637 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over local access with high attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2016-9637 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (28th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-9637?: CVE-2016-9637 primarily affects Citrix Xenserver. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2016-9637?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2016-9637 published?: CVE-2016-9637 was published on 2017-02-17 and last updated on 2026-06-17.

References

Affected products (4)

cpe:2.3:a:citrix:xenserver:6.0.2:*:*:*:*:*:*:*
cpe:2.3:a:citrix:xenserver:6.2.0:sp1:*:*:*:*:*:*
cpe:2.3:a:citrix:xenserver:6.5:sp1:*:*:*:*:*:*
cpe:2.3:a:citrix:xenserver:7.0:*:*:*:*:*:*:*

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