Microsoft Security Response CenterCVE-2026-69781

Windows DHCP Client Denial of Service Vulnerability

Missing release of memory after effective lifetime in Windows DHCP Client allows an unauthorized attacker to deny service over an adjacent network.

Read the vendor bulletin Get alerts for Windows Server 2025 (Server Core installation)

6.5CVSS out of 10High severity

Scope

What the vendor says is affected

Windows Server 2025 (Server Core installation)
Windows 11 Version 25H2 for ARM64-based Systems
Windows 11 Version 25H2 for x64-based Systems
Windows 11 Version 24H2 for ARM64-based Systems
Windows 11 Version 24H2 for x64-based Systems
Windows Server 2025
Windows 11 version 26H1 for x64-based Systems
Windows 11 Version 26H1 for ARM64-based Systems

Versions the vendor lists as fixed

10.0.26100.33438
10.0.26200.9445
10.0.26100.9445
10.0.28000.2954

Next step

What the vendor recommends

Install KB5122871. Install KB5124008. Install KB5124012.

Review the complete instructions on the vendor's site

Timeline

When this advisory changed

Sep 8, 2026 at 7:00 AM UTC
Published by Microsoft Security Response Center
The publication date reported by the vendor.
Sep 8, 2026 at 7:15 PM UTC
Added to SecurityAlert
We collected the advisory from the official source.
Sep 13, 2026 at 2:40 AM UTC
Confirmed at the source
Our collector saw this advisory during a later source check.

Vulnerabilities

CVEs named in this advisory

CVE-2026-69781View CVSS, KEV, EPSS, and threat context

Source

Start with the vendor's bulletin

SecurityAlert organizes the fields the vendor published. The original bulletin remains the source of record for affected versions, fixes, and later changes.

Vendor: Microsoft Security Response Center
Advisory ID: CVE-2026-69781
Last source check: Sep 13, 2026 at 2:40 AM UTC

Open the official bulletin How SecurityAlert builds this record

Your environment

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Read the vendor's prerequisites and exceptions.
Test the update or mitigation through your normal change process.

Watch Windows Server 2025 (Server Core installation)

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What the vendor says is affected

Versions the vendor lists as fixed

What the vendor recommends

When this advisory changed

CVEs named in this advisory

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