How severe is CVE-2017-0021?

CVE-2017-0021 has a CVSS 3.x base score of 9.0, rated critical severity. It is exploitable over an adjacent network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2017-0021 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (75th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2017-0021?

CVE-2017-0021 primarily affects Microsoft Windows 10. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2017-0021?

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

When was CVE-2017-0021 published?

CVE-2017-0021 was published on 2017-03-17 and last updated on 2026-06-17.

CVE-2017-0021

CVE-2017-0021 is a critical-severity vulnerability in Microsoft Windows 10 with a CVSS 3.x base score of 9.0. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: Critical (CVSS 3.x base score 9.0)
CVSS v2: 7.7
EPSS exploit prediction: 2% (75th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Microsoft Windows 10
Published: 2017-03-17
Last modified: 2026-06-17

Description

Hyper-V in Microsoft Windows 10 1607 and Windows Server 2016 does not properly validate vSMB packet data, which allows attackers to execute arbitrary code on a target OS, aka "Hyper-V System Data Structure Vulnerability." This vulnerability is different from that described in CVE-2017-0095.

Frequently asked questions

What is CVE-2017-0021?: Hyper-V in Microsoft Windows 10 1607 and Windows Server 2016 does not properly validate vSMB packet data, which allows attackers to execute arbitrary code on a target OS, aka "Hyper-V System Data Structure Vulnerability." This vulnerability is different from that described in CVE-2017-0095.
How severe is CVE-2017-0021?: CVE-2017-0021 has a CVSS 3.x base score of 9.0, rated critical severity. It is exploitable over an adjacent network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2017-0021 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (75th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2017-0021?: CVE-2017-0021 primarily affects Microsoft Windows 10. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2017-0021?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2017-0021 published?: CVE-2017-0021 was published on 2017-03-17 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:o:microsoft:windows_10:1607:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2016:*:*:*:*:*:*:*:*

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