CVE-2026-20860

CVE-2026-20860 is a high-severity vulnerability in Microsoft Windows 10 1607 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-843.

Key facts

• Severity: High (CVSS 3.x base score 7.8)
• EPSS exploit prediction: 8% (94th percentile)
• Actively exploited: Not listed in CISA KEV
• EU (EUVD) id: EUVD-2026-2159
• Weakness: CWE-843
• Affected product: Microsoft Windows 10 1607
• Published: 2026-01-13
• Last modified: 2026-07-30

Description

Access of resource using incompatible type ('type confusion') in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.

Frequently asked questions

What is CVE-2026-20860?

Access of resource using incompatible type ('type confusion') in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.

How severe is CVE-2026-20860?

CVE-2026-20860 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-2026-20860 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 8% (94th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-20860?

CVE-2026-20860 primarily affects Microsoft Windows 10 1607. In total, 19 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-20860?

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.

Does CVE-2026-20860 have an EU (EUVD) identifier?

Yes. CVE-2026-20860 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-2159.

When was CVE-2026-20860 published?

CVE-2026-20860 was published on 2026-01-13 and last updated on 2026-07-30.

References

• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20860

Affected products (19)

• cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:x64:*
• cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:x86:*
• cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x64:*
• cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:x86:*
• cpe:2.3:o:microsoft:windows_10_21h2:*:*:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_10_22h2:*:*:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_11_23h2:*:*:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_11_24h2:*:*:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_11_25h2:*:*:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_server_2008:-:sp2:*:*:*:*:x64:*
• cpe:2.3:o:microsoft:windows_server_2008:-:sp2:*:*:*:*:x86:*
• 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_2019:*:*:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_server_2022_23h2:*:*:*:*:*:*:*:*
• cpe:2.3:o:microsoft:windows_server_2025:*:*:*:*:*:*:*:*

More vulnerabilities in Microsoft Windows 10 1607

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