CVE-2026-45596: Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability

Severity: high (CVSS 7.0 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-09 · updated 2026-09-24
Weakness: CWE-416

Description

Use after free in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.

Affected products

Microsoft Windows 10 1607: before 10.0.14393.9234 — fixed in 10.0.14393.9234
Microsoft Windows 10: before 10.0.17763.8880 — fixed in 10.0.17763.8880
Microsoft Windows 10: before 10.0.19044.7417 — fixed in 10.0.19044.7417
Microsoft Windows 10: before 10.0.19045.7417 — fixed in 10.0.19045.7417
Microsoft Windows 11: before 10.0.22631.7219 — fixed in 10.0.22631.7219
Microsoft Windows 11: before 10.0.26100.8655 — fixed in 10.0.26100.8655
Microsoft Windows 11 25H2: before 10.0.26200.8655 — fixed in 10.0.26200.8655
Microsoft Windows 11 version 26H1: before 10.0.28000.2269 — fixed in 10.0.28000.2269
Microsoft Windows Server 2012: r2
Microsoft Windows Server 2016: before 10.0.14393.9234 — fixed in 10.0.14393.9234
Microsoft Windows Server 2019: before 10.0.17763.8880 — fixed in 10.0.17763.8880
Microsoft Windows Server 2022: before 10.0.20348.5256 — fixed in 10.0.20348.5256
Microsoft Windows Server 2025: before 10.0.26100.32995 — fixed in 10.0.26100.32995
Microsoft Windows 10 1607: from 10.0.14393.0 before 10.0.14393.9234 — fixed in 10.0.14393.9234
Microsoft Windows 10: from 10.0.17763.0 before 10.0.17763.8880 — fixed in 10.0.17763.8880
Microsoft Windows 10: from 10.0.19044.0 before 10.0.19044.7417 — fixed in 10.0.19044.7417
Microsoft Windows 10: from 10.0.19045.0 before 10.0.19045.7417 — fixed in 10.0.19045.7417
Microsoft Windows 11: from 10.0.22631.0 before 10.0.22631.7219 — fixed in 10.0.22631.7219
Microsoft Windows 11: from 10.0.26100.0 before 10.0.26100.8655 — fixed in 10.0.26100.8655
Microsoft Windows 11 25H2: from 10.0.26200.0 before 10.0.26200.8655 — fixed in 10.0.26200.8655
Microsoft Windows 11 version 26H1: from 10.0.28000.0 before 10.0.28000.2269 — fixed in 10.0.28000.2269
Microsoft Windows Server 2012: from 6.2.9200.0 before 6.2.9200.26132 — fixed in 6.2.9200.26132
Microsoft Windows Server 2012 R2: from 6.3.9600.0 before 6.3.9600.23228 — fixed in 6.3.9600.23228
Microsoft Windows Server 2016: from 10.0.14393.0 before 10.0.14393.9234 — fixed in 10.0.14393.9234
Microsoft Windows Server 2019: from 10.0.17763.0 before 10.0.17763.8880 — fixed in 10.0.17763.8880
Microsoft Windows Server 2022: from 10.0.20348.0 before 10.0.20348.5256 — fixed in 10.0.20348.5256
Microsoft Windows Server 2025: from 10.0.26100.0 before 10.0.26100.32995 — fixed in 10.0.26100.32995

How to fix

Upgrade to a fixed version: Microsoft Windows 10 1607 10.0.14393.9234; Microsoft Windows 10 10.0.17763.8880; Microsoft Windows 10 10.0.19044.7417; Microsoft Windows 10 10.0.19045.7417; Microsoft Windows 11 10.0.22631.7219; Microsoft Windows 11 10.0.26100.8655; Microsoft Windows 11 25H2 10.0.26200.8655; Microsoft Windows 11 version 26H1 10.0.28000.2269; Microsoft Windows Server 2016 10.0.14393.9234; Microsoft Windows Server 2019 10.0.17763.8880; Microsoft Windows Server 2022 10.0.20348.5256; Microsoft Windows Server 2025 10.0.26100.32995. Check the vendor advisory for mitigations.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-45596

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