Use-After-Free in Windows WinSock Driver Enables Local Privilege Escalation

Publication date: 2026-01-13

Last updated on: 2026-01-13

Assigner: Microsoft Corporation

Description

Free of memory not on the heap in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-01-13

Last Modified

2026-01-13

Generated

2026-07-06

AI Q&A

2026-01-14

EPSS Evaluated

2026-07-05

NVD

CVE-2026-20810

Affected Vendors & Products

Vendor	Product	Version / Range
microsoft	windows_ancillary_function_driver_for_winsock	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-590	The product calls free() on a pointer to memory that was not allocated using associated heap allocation functions such as malloc(), calloc(), or realloc().

Attack-Flow Graph

Executive Summary

This vulnerability is a 'free of memory not on the heap' issue in the Windows Ancillary Function Driver for WinSock. It allows an authorized attacker to locally elevate their privileges on the affected system.

Impact Analysis

An attacker who already has some level of access to the system could exploit this vulnerability to gain higher privileges, potentially allowing them to execute unauthorized actions, access sensitive data, or compromise system integrity.

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