CVE-2026-20860: Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability

Published Jan 13, 2026
·
Updated

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

Other sources

Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability

Microsoft

Affected Software

54 affected componentsFixes available
Microsoft Windows 10 1607<10.0.14393.8783
Microsoft Windows 10 1607<10.0.14393.8783
Microsoft Windows 10 1809<10.0.17763.8276
Microsoft Windows 10 1809<10.0.17763.8276
Microsoft Windows 10 21h2<10.0.19044.6809
Microsoft Windows 10 22h2<10.0.19045.6809
Microsoft Windows 11 23h2<10.0.22631.6491
Microsoft Windows 11 24h2<10.0.26100.7623
Microsoft Windows 11 25h2<10.0.26200.7623
Microsoft Windows Server 2008=sp2
Microsoft Windows Server 2008=sp2
Microsoft Windows Server 2008=r2-sp1
Microsoft Windows Server 2012
Microsoft Windows Server 2012=r2
Microsoft Windows Server 2016<10.0.14393.8783
Microsoft Windows Server 2019<10.0.17763.8276
Microsoft Windows Server 2022<10.0.20348.4648
Microsoft Windows Server 2022 23h2<10.0.25398.2092
Microsoft Windows Server 2025<10.0.26100.32230
Microsoft Windows Server 2008<6.0.6003.23717
6.0.6003.23717
Microsoft Windows Server 2008<6.0.6003.23717
6.0.6003.23717
Microsoft Windows Server 2008<6.0.6003.23717
6.0.6003.23717
Microsoft Windows Server 2008 R2<6.1.7601.28117
6.1.7601.28117
Microsoft Windows Server 2008<6.0.6003.23717
6.0.6003.23717
Microsoft Windows Server 2016<10.0.14393.8783
10.0.14393.8783
Microsoft Windows 11=24H2
10.0.26100.7623
Microsoft Windows Server 2008 R2<6.1.7601.28117
6.1.7601.28117
Microsoft Windows Server 2012 R2<6.3.9600.22968
6.3.9600.22968
Microsoft Windows Server 2025<10.0.26100.32230
10.0.26100.32230
Microsoft Windows 10=1607
10.0.14393.8783
Microsoft Windows Server 2012 R2<6.3.9600.22968
6.3.9600.22968
Microsoft Windows Server 2012<6.2.9200.25868
6.2.9200.25868
Microsoft Windows 11=25H2
10.0.26200.7623
Microsoft Windows Server 2022, 23H2 Edition<10.0.25398.2092
10.0.25398.2092
Microsoft Windows 11=23H2
10.0.22631.6491
Microsoft Windows 11=24H2
10.0.26100.7623
Microsoft Windows Server 2016<10.0.14393.8783
10.0.14393.8783
Microsoft Windows 11=25H2
10.0.26200.7623
Microsoft Windows 11=23H2
10.0.22631.6491
Microsoft Windows 10=1607
10.0.14393.8783
Microsoft Windows Server 2025<10.0.26100.32230
10.0.26100.32230
Microsoft Windows 10=22H2
10.0.19045.6809
Microsoft Windows 10=21H2
10.0.19044.6809
Microsoft Windows 10=22H2
10.0.19045.6809
Microsoft Windows 10=22H2
10.0.19045.6809
Microsoft Windows Server 2012<6.2.9200.25868
6.2.9200.25868
Microsoft Windows Server 2022<10.0.20348.4648
10.0.20348.4648
Microsoft Windows Server 2019<10.0.17763.8276
10.0.17763.8276
Microsoft Windows Server 2019<10.0.17763.8276
10.0.17763.8276
Microsoft Windows 10=21H2
10.0.19044.6809
Microsoft Windows Server 2022<10.0.20348.4648
10.0.20348.4648
Microsoft Windows 10=21H2
10.0.19044.6809
Microsoft Windows 10=1809
10.0.17763.8276
Microsoft Windows 10=1809
10.0.17763.8276

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 6.0.6003.23717Patch KB5073700
  2. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 6.1.7601.28117Patch KB5073699
  3. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 10.0.14393.8783Patch KB5073722
  4. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 10.0.26100.7623Patch KB5074109
  5. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 6.3.9600.22968Patch KB5073696
  6. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 10.0.26100.32230Patch KB5073379
  7. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 6.2.9200.25868Patch KB5073698
  8. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 10.0.26200.7623Patch KB5074109
  9. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 10.0.25398.2092Patch KB5073450
  10. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 10.0.22631.6491Patch KB5073455
  11. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 10.0.19045.6809Patch KB5073724
  12. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 10.0.19044.6809Patch KB5073724
  13. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 10.0.20348.4648Patch KB5073457
  14. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 10.0.17763.8276Patch KB5073723

Event History

Jan 13, 2026
CVE Published
via Microsoft·04:00 PM
Data Sourced
via Microsoft·04:00 PM
DescriptionSeverityWeakness
Data Sourced
via Microsoft·04:00 PM
Affected Software
Updated
via Microsoft·04:00 PM
Affected Software
Updated
via Microsoft·04:00 PM
Description
CVE Published
via MITRE·05:56 PM
Data Sourced
via MITRE·05:56 PM
DescriptionSeverity
Data Sourced
via NVD·06:16 PM
DescriptionSeverityWeaknessAffected Software
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Frequently Asked Questions

1

What is the severity of CVE-2026-20860?

CVE-2026-20860 is classified as an elevation of privilege vulnerability.

2

How do I fix CVE-2026-20860?

To fix CVE-2026-20860, apply the Microsoft security updates available for affected Windows products.

3

Which products are affected by CVE-2026-20860?

CVE-2026-20860 affects various versions of Windows Server 2008, 2012, 2016, Windows 10, and Windows 11.

4

Can CVE-2026-20860 be exploited remotely?

CVE-2026-20860 requires local access for exploitation, meaning it cannot be exploited remotely.

5

What types of attacks can leverage CVE-2026-20860?

CVE-2026-20860 can be leveraged to perform local privilege escalation attacks by an authorized user.

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