CVE-2026-40405

Published: May 12, 2026Modified: Jun 17, 2026

7.5

Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Exploitability: 3.9 / Impact: 3.6

Source: secure@microsoft.com (Secondary)

Description

Null pointer dereference in Windows TCP/IP allows an unauthorized attacker to deny service over a network.

Affected (7)

Products: Microsoft: Windows 11 24h2, Windows 11 25h2, Windows 11 26h1, Windows Server 2025

4 products

Windows 11 24h2

Windows 11 25h2

Windows 11 26h1

Windows Server 2025

Configuration A

7 vulnerable

Vulnerable Software	Affected Versions
Microsoft Windows 11 24h2	Before 10.0.26100.8390
Microsoft Windows 11 24h2	Before 10.0.26100.8390
Microsoft Windows 11 25h2	Before 10.0.26200.8390
Microsoft Windows 11 25h2	Before 10.0.26200.8390
Microsoft Windows 11 26h1	Before 10.0.28000.2113
Microsoft Windows 11 26h1	Before 10.0.28000.2113
Microsoft Windows Server 2025	Before 10.0.26100.32772

Related CWEs

NULL Pointer Dereference

The product dereferences a pointer that it expects to be valid but is NULL.

References (1)

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

Source: secure@microsoft.com

Vendor Advisory

Timeline

No history available yet.