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Description

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

PUBLISHED Reserved 2025-12-11 | Published 2026-02-10 | Updated 2026-02-23 | Assigner microsoft




LOW: 3.3CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C

Problem types

CWE-73: External Control of File Name or Path

Product status

10.0.14393.0 (custom) before 10.0.14393.8868
affected

10.0.17763.0 (custom) before 10.0.17763.8389
affected

10.0.19044.0 (custom) before 10.0.19044.6937
affected

10.0.19045.0 (custom) before 10.0.19045.6937
affected

10.0.22631.0 (custom) before 10.0.22631.6649
affected

10.0.22631.0 (custom) before 10.0.22631.6649
affected

10.0.26100.0 (custom) before 10.0.26100.7840
affected

10.0.26200.0 (custom) before 10.0.26200.7840
affected

10.0.28000.0 (custom) before 10.0.28000.1575
affected

10.0.28000.0 (custom) before 10.0.28000.1575
affected

6.3.9600.0 (custom) before 6.3.9600.23022
affected

6.3.9600.0 (custom) before 6.3.9600.23022
affected

10.0.14393.0 (custom) before 10.0.14393.8868
affected

10.0.14393.0 (custom) before 10.0.14393.8868
affected

10.0.17763.0 (custom) before 10.0.17763.8389
affected

10.0.17763.0 (custom) before 10.0.17763.8389
affected

10.0.20348.0 (custom) before 10.0.20348.4773
affected

10.0.25398.0 (custom) before 10.0.25398.2149
affected

10.0.26100.0 (custom) before 10.0.26100.32370
affected

10.0.26100.0 (custom) before 10.0.26100.32370
affected

References

msrc.microsoft.com/update-guide/vulnerability/CVE-2026-21249 (Windows NTLM Spoofing Vulnerability) vendor-advisory patch

cve.org (CVE-2026-21249)

nvd.nist.gov (CVE-2026-21249)

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