Main Vulnerability Database Vulnerabilities #VU131278

NULL pointer dereference in Microsoft Windows and Windows Server - CVE-2026-40405

Published: May 12, 2026

Vulnerability identifier: #VU131278

CSH Severity: Medium

CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-40405

CWE-ID: CWE-476

Exploitation vector: Remote access

Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a NULL pointer dereference error in Windows TCP/IP. A remote attacker can pass specially crafted data to the application and perform a denial of service (DoS) attack.

Affected software

Microsoft Windows
Windows Server

How to mitigate CVE-2026-40405

Install updates from vendor's website.

Microsoft Windows - addressed in versions 11 24H2 10.0.26100.8390, 11 24H2 10.0.26100.8457, 11 25H2 10.0.26200.8390, 11 25H2 10.0.26200.8457, 11 26H1 10.0.28000.2113
Windows Server - addressed in versions 2025 10.0.26100.32772, 2025 10.0.26100.32860

External References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40405

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