CVE-2025-59242: Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-10-14 · updated 2026-06-17
Weakness: CWE-122

Description

Heap-based buffer overflow in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.

Affected products

Microsoft Windows 10 Version 1507: before 10.0.10240.21161 — fixed in 10.0.10240.21161
Microsoft Windows 10 1607: before 10.0.14393.8519 — fixed in 10.0.14393.8519
Microsoft Windows 10: before 10.0.17763.7919 — fixed in 10.0.17763.7919
Microsoft Windows 10: before 10.0.19044.6456 — fixed in 10.0.19044.6456
Microsoft Windows 10: before 10.0.19045.6456 — fixed in 10.0.19045.6456
Microsoft Windows 11: before 10.0.22621.6060 — fixed in 10.0.22621.6060
Microsoft Windows 11: through 10.0.22631.6060
Microsoft Windows 11: before 10.0.26100.6899 — fixed in 10.0.26100.6899
Microsoft Windows 11 25H2: before 10.0.26200.6899 — fixed in 10.0.26200.6899
Microsoft Windows Server 2008: r2-sp1
Microsoft Windows Server 2012: r2
Microsoft Windows Server 2016: through 10.0.14393.8519
Microsoft Windows Server 2019: before 10.0.17763.7919 — fixed in 10.0.17763.7919
Microsoft Windows Server 2022: before 10.0.20348.4294 — fixed in 10.0.20348.4294
Microsoft Windows Server 2022, 23H2 Edition (Server Core installation): before 10.0.25398.1913 — fixed in 10.0.25398.1913
Microsoft Windows Server 2025: through 10.0.26100.6899

How to fix

Upgrade to a fixed version: Microsoft Windows 10 Version 1507 10.0.10240.21161; Microsoft Windows 10 1607 10.0.14393.8519; Microsoft Windows 10 10.0.17763.7919; Microsoft Windows 10 10.0.19044.6456; Microsoft Windows 10 10.0.19045.6456; Microsoft Windows 11 10.0.22621.6060; Microsoft Windows 11 10.0.26100.6899; Microsoft Windows 11 25H2 10.0.26200.6899; Microsoft Windows Server 2019 10.0.17763.7919; Microsoft Windows Server 2022 10.0.20348.4294; Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.1913. Check the vendor advisory for mitigations.

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-59242

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