Feb 2026: Windows NTLM Spoofing Vulnerability
CVE-2026-21249 Published on February 10, 2026

Windows NTLM Spoofing Vulnerability
External control of file name or path in Windows NTLM allows an unauthorized attacker to perform spoofing locally.

Vendor Advisory NVD

Weakness Type

External Control of File Name or Path

The software allows user input to control or influence paths or file names that are used in filesystem operations.

Products Associated with CVE-2026-21249

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Microsoft Windows 11 26h1

Microsoft Windows 10

Microsoft Windows Server 2019

Microsoft Windows Server 2022

Microsoft Windows Server 2025

Microsoft Windows 11 25h2

Microsoft Windows 11 23h2

Microsoft Windows Server 23h2

Microsoft Windows 11 24h2

Microsoft Windows Server 2016

Microsoft Windows Server 2012 R2

Affected Versions

Microsoft Windows 10 Version 1607:

Version 10.0.14393.0 and below 10.0.14393.8868 is affected.

Microsoft Windows 10 Version 1809:

Version 10.0.17763.0 and below 10.0.17763.8389 is affected.

Microsoft Windows 10 Version 21H2:

Version 10.0.19044.0 and below 10.0.19044.6937 is affected.

Microsoft Windows 10 Version 22H2:

Version 10.0.19045.0 and below 10.0.19045.6937 is affected.

Microsoft Windows 11 version 22H3:

Version 10.0.22631.0 and below 10.0.22631.6649 is affected.

Microsoft Windows 11 Version 23H2:

Version 10.0.22631.0 and below 10.0.22631.6649 is affected.

Microsoft Windows 11 Version 24H2:

Version 10.0.26100.0 and below 10.0.26100.7840 is affected.

Microsoft Windows 11 Version 25H2:

Version 10.0.26200.0 and below 10.0.26200.7840 is affected.

Microsoft Windows 11 version 26H1:

Version 10.0.28000.0 and below 10.0.28000.1575 is affected.

Microsoft Windows 11 Version 26H1:

Version 10.0.28000.0 and below 10.0.28000.1575 is affected.

Microsoft Windows Server 2012 R2:

Version 6.3.9600.0 and below 6.3.9600.23022 is affected.

Microsoft Windows Server 2012 R2 (Server Core installation):

Version 6.3.9600.0 and below 6.3.9600.23022 is affected.

Microsoft Windows Server 2016:

Version 10.0.14393.0 and below 10.0.14393.8868 is affected.

Microsoft Windows Server 2016 (Server Core installation):

Version 10.0.14393.0 and below 10.0.14393.8868 is affected.

Microsoft Windows Server 2019:

Version 10.0.17763.0 and below 10.0.17763.8389 is affected.

Microsoft Windows Server 2019 (Server Core installation):

Version 10.0.17763.0 and below 10.0.17763.8389 is affected.

Microsoft Windows Server 2022:

Version 10.0.20348.0 and below 10.0.20348.4773 is affected.

Microsoft Windows Server 2022, 23H2 Edition (Server Core installation):

Version 10.0.25398.0 and below 10.0.25398.2149 is affected.

Microsoft Windows Server 2025:

Version 10.0.26100.0 and below 10.0.26100.32370 is affected.

Microsoft Windows Server 2025 (Server Core installation):

Version 10.0.26100.0 and below 10.0.26100.32370 is affected.

Exploit Probability

EPSS

0.04%

Percentile

13.25%