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Microsoft Security Response CenterCVE-2026-61366

Windows Network Connection Broker Elevation of Privilege Vulnerability

Double free in Windows Network Connection Broker allows an authorized attacker to elevate privileges locally.

Read the vendor bulletin Get alerts for Windows
7.0CVSS out of 10High severity
Scope

What the vendor says is affected

  • Windows 10 Version 1809 for 32-bit Systems
  • Windows 10 Version 1809 for x64-based Systems
  • Windows Server 2019
  • Windows Server 2019 (Server Core installation)
  • Windows Server 2022
  • Windows Server 2022 (Server Core installation)
  • Windows 10 Version 21H2 for 32-bit Systems
  • Windows 10 Version 21H2 for ARM64-based Systems
  • Windows 10 Version 21H2 for x64-based Systems
  • Windows 10 Version 22H2 for x64-based Systems
  • Windows 10 Version 22H2 for ARM64-based Systems
  • Windows 10 Version 22H2 for 32-bit Systems
  • 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 23H2 for ARM64-based Systems
  • Windows 11 Version 23H2 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
  • Windows 10 Version 1607 for 32-bit Systems
  • Windows 10 Version 1607 for x64-based Systems

Versions the vendor lists as fixed

  • 10.0.17763.9121
  • 10.0.20348.5499
  • 10.0.20348.5440
  • 10.0.19044.7663
  • 10.0.19045.7663
  • 10.0.26100.33296
  • 10.0.26100.33222
  • 10.0.26200.9168
  • 10.0.26200.9106
  • 10.0.22631.7517
  • 10.0.26100.9168
  • 10.0.26100.9106
  • 10.0.28000.2704
  • 10.0.14393.9418
  • 6.2.9200.26280
  • 6.3.9600.23338
Next step

What the vendor recommends

Install KB5120238. Install KB5120242. Install KB5120229. Install KB5120249. Install KB5120233. Install KB5120228. Install KB5121003. Install KB5120994. Install KB5120240. Install KB5121000. Install KB5120418. Install KB5120386. Install KB5120385.

Review the complete instructions on the vendor's site
Update history

What changed in later vendor updates

SecurityAlert records field-level changes from the point we begin following a bulletin. Earlier vendor changes may not have a field-by-field record.

    • The vendor changed its remediation guidance.
Timeline

When this advisory changed

  1. Published by Microsoft Security Response Center

    The publication date reported by the vendor.

  2. Added to SecurityAlert

    We collected the advisory from the official source.

  3. Confirmed at the source

    Our collector saw this advisory during a later source check.

Vulnerabilities

CVEs named in this advisory

CVE-2026-61366View CVSS, KEV, EPSS, and threat context
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