Heap-Based Buffer Overflow in Windows CLFS Driver Enables Privilege Escalation

Publication date: 2026-01-13

Last updated on: 2026-01-13

Assigner: Microsoft Corporation

Description

Heap-based buffer overflow in Windows Common Log File System Driver 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-2026-20820

Affected Vendors & Products

Vendor	Product	Version / Range
microsoft	windows_common_log_file_system_driver	*

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().

Attack-Flow Graph

Impact Analysis

An attacker who is already authorized on the system can exploit this vulnerability to gain higher privileges, potentially allowing them to execute code with elevated rights, access sensitive data, or make unauthorized changes to the system.

Executive Summary

This vulnerability is a heap-based buffer overflow in the Windows Common Log File System Driver. It allows an authorized attacker to locally elevate their privileges on the affected system.

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