TOCTOU Race Condition in Windows Kernel Enables Local Privilege Escalation

Publication date: 2026-01-13

Last updated on: 2026-01-13

Assigner: Microsoft Corporation

Description

Time-of-check time-of-use (toctou) race condition in Windows Kernel Memory 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-2026-20809

Affected Vendors & Products

Vendor	Product	Version / Range
microsoft	windows_kernel	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-122	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().
CWE-367	The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check.

Attack-Flow Graph

Executive Summary

This vulnerability is a time-of-check time-of-use (toctou) race condition in the Windows Kernel Memory. It allows an authorized attacker to exploit the timing between checking a condition and using a resource, leading to an elevation of privileges locally on the affected system. [1]

Impact Analysis

The vulnerability can allow an authorized attacker to elevate their privileges on the local system. This means the attacker could gain higher-level access than intended, potentially leading to unauthorized actions, data access, or system control. [1]

Mitigation Strategies

Apply the security updates provided by Microsoft for this vulnerability as soon as possible to mitigate the elevation of privilege risk caused by the toctou race condition in Windows Kernel Memory. [1]

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