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PatchSiren cyber security CVE debrief

CVE-2026-56159 Microsoft CVE debrief

A heap-based buffer overflow vulnerability exists in the Windows DHCP Server, allowing an unauthorized attacker to execute code over a network. The vulnerability has a CVSS score of 9.8 and is classified as CRITICAL. System administrators and security teams responsible for Windows DHCP Server installations should be aware of this critical vulnerability. The CVE record was published on 2026-07-14T18:18:22.797Z and has not been modified since then. The NVD entry is currently Analyzed. This vulnerability affects Windows DHCP Server installations, and its exploitation could lead to code execution over a network.

Vendor
Microsoft
Product
Windows 10 Version 1607
CVSS
CRITICAL 9.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-14
Original CVE updated
2026-07-21
Advisory published
2026-07-14
Advisory updated
2026-07-21

Who should care

System administrators and security teams responsible for Windows DHCP Server installations should be aware of this critical vulnerability. They should review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance. They should also plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.

Technical summary

A heap-based buffer overflow vulnerability exists in the Windows DHCP Server, allowing an unauthorized attacker to execute code over a network. The vulnerability has a CVSS score of 9.8 and is classified as CRITICAL. The vulnerability is caused by a heap-based buffer overflow in the Windows DHCP Server, which allows an attacker to execute code over a network. The affected product is Windows DHCP Server, and the vulnerability has a high impact on confidentiality, integrity, and availability.

Defensive priority

Immediate attention is required to patch vulnerable Windows DHCP Server installations to prevent potential code execution.

Recommended defensive actions

  • Apply the vendor-provided patch for CVE-2026-56159
  • Conduct an inventory check to identify vulnerable Windows DHCP Server installations
  • Implement compensating controls, such as network segmentation and monitoring, to reduce the attack surface
  • Review compensating controls for exposed systems while remediation is scheduled and verified
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review

Evidence notes

The CVE record and NVD detail provide information on the vulnerability, including its CVSS score and affected systems. However, further analysis is required to fully understand the vulnerability's impact and to develop effective mitigations. The evidence is limited to the CVE record and NVD detail, and defenders should verify the affected scope and severity of the vulnerability.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-56159 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-56159

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-56159 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-56159

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.