CVE-2026-40405 — HIGH (7.5)

Q: What is CVE-2026-40405?

CVE-2026-40405 is a vulnerability with a CVSS score of 7.5 (HIGH). Null pointer dereference in Windows TCP/IP allows an unauthorized attacker to deny service over a network.

Q: How severe is CVE-2026-40405?

CVE-2026-40405 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.

Q: Is there a patch for CVE-2026-40405?

Check the references section above for vendor advisories and patch information. Affected products include: Microsoft Windows 11 24H2, Microsoft Windows 11 25H2, Microsoft Windows 11 26H1, Microsoft Windows Server 2025.

Vulnerability Description

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

CVSS Score

7.5

HIGH

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

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality

NONE

Integrity

NONE

Availability

HIGH

Affected Products

Vendor	Product	Versions
Microsoft	Windows 11 24H2	< 10.0.26100.8390
Microsoft	Windows 11 25H2	< 10.0.26200.8390
Microsoft	Windows 11 26H1	< 10.0.28000.2113
Microsoft	Windows Server 2025	< 10.0.26100.32772

Related Weaknesses (CWE)

CWE-476

References

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

FAQ

What is CVE-2026-40405?

CVE-2026-40405 is a vulnerability with a CVSS score of 7.5 (HIGH). Null pointer dereference in Windows TCP/IP allows an unauthorized attacker to deny service over a network.

How severe is CVE-2026-40405?

CVE-2026-40405 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-40405?

Check the references section above for vendor advisories and patch information. Affected products include: Microsoft Windows 11 24H2, Microsoft Windows 11 25H2, Microsoft Windows 11 26H1, Microsoft Windows Server 2025.