CVE-2026-20820

HIGH

Windows Common Log File System Driver - Buffer Overflow

Title source: llm

Exploitation Summary

EIP tracks 1 public exploit for CVE-2026-20820. PoCs published by uname1able.

AI-analyzed exploit summary This PoC exploits an out-of-bounds (OOB) write vulnerability in the Common Log File System (CLFS) driver by sending a crafted IOCTL request to trigger memory corruption. The exploit manipulates buffer boundaries to achieve the OOB write, targeting Windows 10/11 systems.

Description

Heap-based buffer overflow in Windows Common Log File System Driver allows an authorized attacker to elevate privileges locally.

Exploits (1)

nomisec WORKING POC

by uname1able · poc

https://github.com/uname1able/CVE-2026-20820

View Code ZIP pw:eip

This PoC exploits an out-of-bounds (OOB) write vulnerability in the Common Log File System (CLFS) driver by sending a crafted IOCTL request to trigger memory corruption. The exploit manipulates buffer boundaries to achieve the OOB write, targeting Windows 10/11 systems.

Classification

Working Poc 95%

Attack Type

Lpe

Complexity

Moderate

Reliability

Reliable

Target: Microsoft Windows CLFS Driver (win10_21h2_19044.6693_amd64, win11_23h2_22631.6345_amd64)

No auth needed

Prerequisites: Windows SDK 10.0 · Visual Studio 2022 · CLFS driver access

MITRE ATT&CK

T1068 - Exploitation for Privilege Escalation T1548 - Abuse Elevation Control Mechanism

devstral-2 · analyzed Mar 18, 2026 Full analysis →

References (1)

Core 1

Core References

Vendor Advisory vendor-advisory patch

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-20820

Scores

CVSS v3 7.8

EPSS 0.0252

EPSS Percentile 82.8%

Attack Vector LOCAL

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CISA SSVC

Vulnrichment

Exploitation none

Automatable no

Technical Impact total

Details

CWE

CWE-122

Status published

Products (40)

Microsoft/Windows 10 Version 1607 10.0.14393.0 - 10.0.14393.8783

Microsoft/Windows 10 Version 1809 10.0.17763.0 - 10.0.17763.8276

Microsoft/Windows 10 Version 21H2 10.0.19044.0 - 10.0.19044.6809

Microsoft/Windows 10 Version 22H2 10.0.19045.0 - 10.0.19045.6809

Microsoft/Windows 11 version 22H3 10.0.22631.0 - 10.0.22631.6491

Microsoft/Windows 11 Version 23H2 10.0.22631.0 - 10.0.22631.6491

Microsoft/Windows 11 Version 24H2 10.0.26100.0 - 10.0.26100.7623

Microsoft/Windows 11 Version 25H2 10.0.26200.0 - 10.0.26200.7623

Microsoft/Windows Server 2008 R2 Service Pack 1 6.1.7601.0 - 6.1.7601.28117

Microsoft/Windows Server 2008 R2 Service Pack 1 (Server Core installation) 6.1.7601.0 - 6.1.7601.28117

... and 30 more

Published Jan 13, 2026

Tracked Since Feb 18, 2026