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HIGH · 7.8

CVE-2026-40399

Stack-based buffer overflow in Windows TCP/IP allows an authorized attacker to elevate privileges locally.

Vulnerability Description

Stack-based buffer overflow in Windows TCP/IP allows an authorized attacker to elevate privileges locally.

CVSS Score

7.8

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH

Affected Products

VendorProductVersions
MicrosoftWindows 10 1607< 10.0.14393.9140
MicrosoftWindows 10 1809< 10.0.17763.8755
MicrosoftWindows 10 21H2< 10.0.19044.7291
MicrosoftWindows 10 22H2< 10.0.19045.7291
MicrosoftWindows 11 23H2< 10.0.22631.7079
MicrosoftWindows 11 24H2< 10.0.26100.8390
MicrosoftWindows 11 25H2< 10.0.26200.8390
MicrosoftWindows 11 26H1< 10.0.28000.2113
MicrosoftWindows Server 2016< 10.0.14393.9140
MicrosoftWindows Server 2019< 10.0.17763.8755
MicrosoftWindows Server 2022< 10.0.20348.5074
MicrosoftWindows Server 2022 23H2< 10.0.25398.2330
MicrosoftWindows Server 2025< 10.0.26100.32772

Related Weaknesses (CWE)

CWE-121

References

FAQ

What is CVE-2026-40399?

CVE-2026-40399 is a vulnerability with a CVSS score of 7.8 (HIGH). Stack-based buffer overflow in Windows TCP/IP allows an authorized attacker to elevate privileges locally.

How severe is CVE-2026-40399?

CVE-2026-40399 has been rated HIGH with a CVSS base score of 7.8/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-40399?

Check the references section above for vendor advisories and patch information. Affected products include: Microsoft Windows 10 1607, Microsoft Windows 10 1809, Microsoft Windows 10 21H2, Microsoft Windows 10 22H2, Microsoft Windows 11 23H2.