How severe is CVE-2021-33771?

CVE-2021-33771 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-2021-33771 being actively exploited?

Yes. CVE-2021-33771 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2021-11-03, which means active exploitation has been confirmed. It should be prioritised for remediation.

What products are affected by CVE-2021-33771?

CVE-2021-33771 primarily affects Microsoft Windows 10 1507. In total, 16 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-33771?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.

Does CVE-2021-33771 have an EU (EUVD) identifier?

Yes. CVE-2021-33771 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-20448. It is also flagged as exploited in the EUVD (since 2021-11-03).

When was CVE-2021-33771 published?

CVE-2021-33771 was published on 2021-07-14 and last updated on 2026-06-17.

CVE-2021-33771

CVE-2021-33771 is a high-severity vulnerability in Microsoft Windows 10 1507 with a CVSS 3.x base score of 7.8. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming it has been exploited in the wild (added 2021-11-03).

Key facts

Severity: High (CVSS 3.x base score 7.8)
CVSS v2: 7.2
EPSS exploit prediction: 6% (93rd percentile)
Actively exploited: Yes — listed in CISA KEV (added 2021-11-03)
EU (EUVD) id: EUVD-2021-20448
EU exploitation: Flagged exploited in the ENISA EU Vulnerability Database (since 2021-11-03)
Affected product: Microsoft Windows 10 1507
Published: 2021-07-14
Last modified: 2026-06-17

Description

Windows Kernel Elevation of Privilege Vulnerability

Frequently asked questions

What is CVE-2021-33771?: Windows Kernel Elevation of Privilege Vulnerability
How severe is CVE-2021-33771?: CVE-2021-33771 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-2021-33771 being actively exploited?: Yes. CVE-2021-33771 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2021-11-03, which means active exploitation has been confirmed. It should be prioritised for remediation.
What products are affected by CVE-2021-33771?: CVE-2021-33771 primarily affects Microsoft Windows 10 1507. In total, 16 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-33771?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.
Does CVE-2021-33771 have an EU (EUVD) identifier?: Yes. CVE-2021-33771 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-20448. It is also flagged as exploited in the EUVD (since 2021-11-03).
When was CVE-2021-33771 published?: CVE-2021-33771 was published on 2021-07-14 and last updated on 2026-06-17.

References

Affected products (16)

cpe:2.3:o:microsoft:windows_10_1507:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_10_1909:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_10_2004:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_10_20h2:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_10_21h1:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_8.1:-:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_rt_8.1:-:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2004:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2008:-:sp1:*:*:*:*:x64:*
cpe:2.3:o:microsoft:windows_server_2008:-:sp2:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2012:-:r2:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2016:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*
cpe:2.3:o:microsoft:windows_server_20h2:*:*:*:*:*:*:*:*

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