How severe is CVE-2016-9386?

CVE-2016-9386 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2016-9386 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (36th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-9386?

CVE-2016-9386 primarily affects Citrix Xenserver. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2016-9386?

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-2016-9386 published?

CVE-2016-9386 was published on 2017-01-23 and last updated on 2026-06-17.

CVE-2016-9386

CVE-2016-9386 is a high-severity vulnerability in Citrix Xenserver with a CVSS 3.x base score of 7.8. 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 7.8)
CVSS v2: 4.6
EPSS exploit prediction: 0% (36th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-264
Affected product: Citrix Xenserver
Published: 2017-01-23
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is 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.
How severe is CVE-2016-9386?: CVE-2016-9386 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2016-9386 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (36th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-9386?: CVE-2016-9386 primarily affects Citrix Xenserver. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2016-9386?: 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-2016-9386 published?: CVE-2016-9386 was published on 2017-01-23 and last updated on 2026-06-17.

References

Affected products (5)

cpe:2.3:a:citrix:xenserver:6.0.2:*:*:*:*:*:*:*
cpe:2.3:a:citrix:xenserver:6.2.0:*:*:*:*:*:*:*
cpe:2.3:a:citrix:xenserver:6.5:*:*:*:*:*:*:*
cpe:2.3:a:citrix:xenserver:7.0:*:*:*:*:*:*:*
cpe:2.3:o:xen:xen:*:*:*:*:*:*:*:*

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