# CVE-2026-56159: Microsoft Windows DHCP Server heap overflow remote code execution

Source: https://junglewise.ai/threats/cve-2026-56159-microsoft-windows-dhcp-server-heap-overflow-remote-code-execution  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-14. Updated: 2026-07-14  
License: CC BY 4.0 with a link back

CVE-2026-56159 · Severity: critical · CVSS 9.8 · Published 2026-07-14

A critical vulnerability has been identified in the Windows DHCP Server, a core service that automatically assigns IP addresses to devices on a network. An unauthorized attacker could exploit this flaw over the network to gain full control of the server without any user interaction. This could lead to a complete service outage, data theft, or a foothold for further attacks within the corporate network.

Technologies: [Microsoft Windows Server 2012 R2](https://junglewise.ai/threats/technologies/windows-server-2012-r2), [Microsoft Windows 10](https://junglewise.ai/threats/technologies/windows-10), [Microsoft Windows Server 2012](https://junglewise.ai/threats/technologies/windows-server-2012), [Microsoft Windows Server 2016](https://junglewise.ai/threats/technologies/windows-server-2016), [Microsoft Windows Server 2019](https://junglewise.ai/threats/technologies/windows-server-2019). Vendors: [Microsoft](https://junglewise.ai/threats/vendors/microsoft).

## Quick answers

**Is CVE-2026-56159 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-56159 being exploited in the wild.

**How severe is CVE-2026-56159?** Critical severity, with a CVSS score of 9.8, published 14 July 2026.

**Which products and versions are affected?** Microsoft Windows Server 2012 R2 6.3.9600.0 to 6.3.9600.23290; Microsoft Windows 10 10.0.14393.0 to 10.0.14393.9338; Microsoft Windows Server 2012 6.2.9200.0 to 6.2.9200.26225; Microsoft Windows Server 2016 10.0.14393.0 to 10.0.14393.9338; and 1 more.

**Is there a fix for CVE-2026-56159?** A patch was published on 2026-07-14: Security updates released by Microsoft. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-56159 attacked?** It is attacked over the network, in an operating system.

**Am I affected by CVE-2026-56159?** Check whether you run Microsoft Windows Server 2012 R2, Microsoft Windows 10, Microsoft Windows Server 2012 or one of the others listed at an affected version. 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 heap-based buffer overflow vulnerability (CWE-122) exists in the Microsoft Windows DHCP Server service. The flaw is triggered when the service improperly handles specially crafted DHCP packets sent over the network. An unauthenticated, remote attacker can exploit this by sending malicious requests to a vulnerable server, leading to arbitrary code execution in the context of the service. The vulnerability is highly automatable and requires no user interaction. Microsoft has released security updates to address this issue across affected Windows and Windows Server versions.

## Affected products

- Microsoft Windows 10 Version 1607 10.0.14393.0 to 10.0.14393.9338
- Microsoft Windows 10 Version 1809 10.0.17763.0 to 10.0.17763.9019
- Microsoft Windows Server 2012 6.2.9200.0 to 6.2.9200.26225
- Microsoft Windows Server 2012 R2 6.3.9600.0 to 6.3.9600.23290
- Microsoft Windows Server 2016 10.0.14393.0 to 10.0.14393.9338
- Microsoft Windows Server 2019 10.0.17763.0 to 10.0.17763.9019

## Timeline

- 2026-07-14: advisory: Microsoft published the security advisory and NVD entry.
- 2026-07-14: patched: Security updates released by Microsoft.

## References

- [https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56159](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56159)

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