CVE-2021-43240: NTFS Set Short Name Elevation of Privilege Vulnerability

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-12-15 · updated 2026-06-17

Description

NTFS Set Short Name Elevation of Privilege Vulnerability

Affected products

Microsoft Windows 10 Version 1607: 20h2, 21h1, 21h2, 1909, 2004
Microsoft Windows 11 version 21H2: all versions
Microsoft Windows Server: 20h2, 2022
Microsoft Windows Server 2016: 2004
Microsoft Windows 10 1909: from 10.0.0 before 10.0.18363.1977 — fixed in 10.0.18363.1977
Microsoft Windows 10 2004: from 10.0.0 before 10.0.19041.1415 — fixed in 10.0.19041.1415
Microsoft Windows 10 20H2: from 10.0.0 before 10.0.19042.1415 — fixed in 10.0.19042.1415
Microsoft Windows 10 21H1: from 10.0.0 before 10.0.19043.1415 — fixed in 10.0.19043.1415
Microsoft Windows 10: from 10.0.0 before 10.0.19044.1415 — fixed in 10.0.19044.1415
Microsoft Windows 11 21H2: from 10.0.0 before 10.0.22000.376 — fixed in 10.0.22000.376
Microsoft Windows Server 2022: from 10.0.0 before 10.0.20348.405 — fixed in 10.0.20348.405
Microsoft Windows Server version 2004: from 10.0.0 before 10.0.19041.1415 — fixed in 10.0.19041.1415
Microsoft Windows Server version 20H2: from 10.0.0 before 10.0.19042.1415 — fixed in 10.0.19042.1415

How to fix

Upgrade to a fixed version: Microsoft Windows 10 1909 10.0.18363.1977; Microsoft Windows 10 2004 10.0.19041.1415; Microsoft Windows 10 20H2 10.0.19042.1415; Microsoft Windows 10 21H1 10.0.19043.1415; Microsoft Windows 10 10.0.19044.1415; Microsoft Windows 11 21H2 10.0.22000.376; Microsoft Windows Server 2022 10.0.20348.405; Microsoft Windows Server version 2004 10.0.19041.1415; Microsoft Windows Server version 20H2 10.0.19042.1415. Check the vendor advisory for mitigations.

References

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