Oct 2025: Windows Ancillary Function Driver for WinSock Elevation of Privilege Vulnerability
CVE-2025-59242 Published on October 14, 2025

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

Vendor Advisory NVD

Weakness Types

Heap-based Buffer Overflow

A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().

What is an Integer underflow Vulnerability?

The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result. This can happen in signed and unsigned cases.

CVE-2025-59242 has been classified to as an Integer underflow vulnerability or weakness.

Products Associated with CVE-2025-59242

You can be notified by email with stack.watch whenever vulnerabilities like CVE-2025-59242 are published in these products:

Microsoft Windows 10

Microsoft Windows Server 2019

Microsoft Windows Server 2022

Microsoft Windows 11

Microsoft Windows Server 2025

Microsoft Windows 11 25h2

Microsoft Windows 11 23h2

Microsoft Windows Server 23h2

Microsoft Windows 11 24h2

Microsoft Windows 10 1507

Microsoft Windows Server 2016

Microsoft Windows Server 2008 Sp2

Microsoft Windows Server 2008 R2

Microsoft Windows Server 2012

Microsoft Windows Server 2012 R2

Affected Versions

Microsoft Windows 10 Version 1507:

Version 10.0.10240.0 and below 10.0.10240.21161 is affected.

Microsoft Windows 10 Version 1607:

Version 10.0.14393.0 and below 10.0.14393.8519 is affected.

Microsoft Windows 10 Version 1809:

Version 10.0.17763.0 and below 10.0.17763.7919 is affected.

Microsoft Windows 10 Version 21H2:

Version 10.0.19044.0 and below 10.0.19044.6456 is affected.

Microsoft Windows 10 Version 22H2:

Version 10.0.19045.0 and below 10.0.19045.6456 is affected.

Microsoft Windows 11 version 22H2:

Version 10.0.22621.0 and below 10.0.22621.6060 is affected.

Microsoft Windows 11 version 22H3:

Version 10.0.22631.0 and below 10.0.22631.6060 is affected.

Microsoft Windows 11 Version 23H2:

Version 10.0.22631.0 and below 10.0.22631.6060 is affected.

Microsoft Windows 11 Version 24H2:

Version 10.0.26100.0 and below 10.0.26100.6899 is affected.

Microsoft Windows 11 Version 25H2:

Version 10.0.26200.0 and below 10.0.26200.6899 is affected.

Microsoft Windows Server 2008 R2 Service Pack 1:

Version 6.1.7601.0 and below 6.1.7601.27974 is affected.

Microsoft Windows Server 2008 R2 Service Pack 1 (Server Core installation):

Version 6.1.7601.0 and below 6.1.7601.27974 is affected.

Microsoft Windows Server 2008 Service Pack 2:

Version 6.0.6003.0 and below 6.0.6003.23571 is affected.

Microsoft Windows Server 2008 Service Pack 2 (Server Core installation):

Version 6.0.6003.0 and below 6.0.6003.23571 is affected.

Microsoft Windows Server 2012:

Version 6.2.9200.0 and below 6.2.9200.25722 is affected.

Microsoft Windows Server 2012 (Server Core installation):

Version 6.2.9200.0 and below 6.2.9200.25722 is affected.

Microsoft Windows Server 2012 R2:

Version 6.3.9600.0 and below 6.3.9600.22824 is affected.

Microsoft Windows Server 2012 R2 (Server Core installation):

Version 6.3.9600.0 and below 6.3.9600.22824 is affected.

Microsoft Windows Server 2016:

Version 10.0.14393.0 and below 10.0.14393.8519 is affected.

Microsoft Windows Server 2016 (Server Core installation):

Version 10.0.14393.0 and below 10.0.14393.8519 is affected.

Microsoft Windows Server 2019:

Version 10.0.17763.0 and below 10.0.17763.7919 is affected.

Microsoft Windows Server 2019 (Server Core installation):

Version 10.0.17763.0 and below 10.0.17763.7919 is affected.

Microsoft Windows Server 2022:

Version 10.0.20348.0 and below 10.0.20348.4294 is affected.

Microsoft Windows Server 2022, 23H2 Edition (Server Core installation):

Version 10.0.25398.0 and below 10.0.25398.1913 is affected.

Microsoft Windows Server 2025:

Version 10.0.26100.0 and below 10.0.26100.6899 is affected.

Microsoft Windows Server 2025 (Server Core installation):

Version 10.0.26100.0 and below 10.0.26100.6899 is affected.

Exploit Probability

EPSS

0.15%

Percentile

34.92%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.