# CVE-2026-40414: Microsoft Windows TCP/IP null pointer dereference denial of service

Source: https://junglewise.ai/threats/cve-2026-40414-microsoft-windows-tcp-ip-null-pointer-dereference-denial-of  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-12. Updated: 2026-06-01  
License: CC BY 4.0 with a link back

CVE-2026-40414 · Severity: high · CVSS 7.4 · Published 2026-05-12

A vulnerability in the Windows networking stack could allow an attacker on the same local network to crash a computer or server. This affects the core component responsible for internet and network communications (TCP/IP). An exploit would result in a blue screen or system reboot, causing an immediate service outage and potential data loss for unsaved work.

Technologies: [Microsoft Windows](https://junglewise.ai/threats/technologies/windows). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft).

## Quick answers

**Is CVE-2026-40414 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-40414 being exploited in the wild.

**How severe is CVE-2026-40414?** High severity, with a CVSS score of 7.4, published 12 May 2026.

**Which products and versions are affected?** Microsoft Windows 10 1607, 1809, 21H2, 22H2; Microsoft Windows 11 23H2, 24H2, 25H2, 26H1; Microsoft Windows Server 2012, 2012 R2, 2016, 2019, 2022, 2025, 23H2.

**Is there a fix for CVE-2026-40414?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-40414 attacked?** It is attacked from the adjacent network, in an operating system.

**Am I affected by CVE-2026-40414?** Check whether you run Microsoft Windows. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A NULL pointer dereference (CWE-476) exists within the Windows TCP/IP stack. An unauthenticated attacker located on the same local network or subnet (adjacent vector) can trigger this vulnerability by sending specially crafted network traffic. Successful exploitation results in a system crash (Bug Check), leading to a Denial of Service (DoS) condition. The vulnerability affects a wide range of Windows client and server versions, including Windows 10, Windows 11, and Windows Server 2012 through 2025. Microsoft has released security updates to address this issue.

## Affected products

- Microsoft Windows 10 1607, 1809, 21H2, 22H2
- Microsoft Windows 11 23H2, 24H2, 25H2, 26H1
- Microsoft Windows Server 2012, 2012 R2, 2016, 2019, 2022, 2025, 23H2

## Timeline

- 2026-05-12: disclosed
- 2026-05-12: advisory: Microsoft published the security advisory and update guide.
- 2026-06-01: other: NVD record modified after enrichment.

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40414](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40414)

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