CVE-2021-34516

CVE-2021-34516 is a high-severity vulnerability in Microsoft Windows 10 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-20.

Key facts

• Severity: High (CVSS 3.x base score 7.8)
• CVSS v2: 4.6
• EPSS exploit prediction: 1% (67th percentile)
• Actively exploited: Not listed in CISA KEV
• Weakness: CWE-20
• Affected product: Microsoft Windows 10
• Published: 2021-07-14
• Last modified: 2026-06-17

Description

Win32k Elevation of Privilege Vulnerability

Frequently asked questions

What is CVE-2021-34516?

Win32k Elevation of Privilege Vulnerability

How severe is CVE-2021-34516?

CVE-2021-34516 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-2021-34516 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (67th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-34516?

CVE-2021-34516 primarily affects Microsoft Windows 10. In total, 18 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-34516?

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-2021-34516 published?

CVE-2021-34516 was published on 2021-07-14 and last updated on 2026-06-17.

References

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34516
• https://www.zerodayinitiative.com/advisories/ZDI-21-1004/
• https://www.zerodayinitiative.com/advisories/ZDI-21-1005/
• https://www.zerodayinitiative.com/advisories/ZDI-21-1006/
• https://www.zerodayinitiative.com/advisories/ZDI-21-1007/
• https://www.zerodayinitiative.com/advisories/ZDI-21-1008/
• https://www.zerodayinitiative.com/advisories/ZDI-21-1009/
• https://www.zerodayinitiative.com/advisories/ZDI-21-1010/
• https://www.zerodayinitiative.com/advisories/ZDI-21-1011/
• https://www.zerodayinitiative.com/advisories/ZDI-21-1012/
• https://www.zerodayinitiative.com/advisories/ZDI-21-1013/
• https://www.zerodayinitiative.com/advisories/ZDI-21-1014/
• https://www.zerodayinitiative.com/advisories/ZDI-21-1015/
• https://www.zerodayinitiative.com/advisories/ZDI-21-1016/
• https://www.zerodayinitiative.com/advisories/ZDI-21-1017/
• https://www.zerodayinitiative.com/advisories/ZDI-21-1018/
• https://www.zerodayinitiative.com/advisories/ZDI-21-1019/
• https://www.zerodayinitiative.com/advisories/ZDI-21-1020/
• https://www.zerodayinitiative.com/advisories/ZDI-21-1021/
• https://www.zerodayinitiative.com/advisories/ZDI-21-1022/
• https://www.zerodayinitiative.com/advisories/ZDI-21-895/

Affected products (18)

• cpe:2.3:o:microsoft:windows_10:-:*:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_10:20h2:*:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_10:21h1:*:*:*:*:*:*:*
• 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_7:-:sp1:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_8.1:-:*:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_rt_8.1:-:*:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_server_2008:-:sp2:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_server_2008:r2:sp1:*:*:*:*:x64:*
• cpe:2.3:o:microsoft:windows_server_2012:-:*:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_server_2012:r2:*:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_server_2016:-:*:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_server_2016:20h2:*:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_server_2016:2004:*:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_server_2019:-:*:*:*:*:*:*:*

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