Windows Network Policy Server: Use-after-free remote code execution

Summary

Microsoft Windows Network Policy Server (NPS), the RADIUS and network access policy component of Windows Server, contains a use-after-free vulnerability (CWE-416). An unauthenticated attacker on the network can exploit it to execute code. The CVSS base score is 8.1 (High) with high attack complexity. Exposure depends on whether an NPS server is reachable from untrusted networks.

Affected

• Windows 10 Version 1607 (10.0.14393.0 before 10.0.14393.9612)
• Windows 10 Version 1809 (10.0.17763.0 before 10.0.17763.9376)
• Windows 10 Version 21H2 (10.0.19044.0 before 10.0.19044.7807)
• Windows 10 Version 22H2 (10.0.19045.0 before 10.0.19045.7807)
• Windows 11 Version 23H2 (10.0.22631.0 before 10.0.22631.7652)
• Windows 11 Version 24H2 (10.0.26100.0 before 10.0.26100.9711)
• Windows 11 Version 25H2 (10.0.26200.0 before 10.0.26200.9711)
• Windows 11 Version 26H1 (10.0.28000.0 before 10.0.28000.3231)
• Windows 11 Version 26H2 (10.0.26300.0 before 10.0.26300.9711)
• Windows Server 2012 and Server Core installation (6.2.9200.0 before 6.2.9200.26434)
• Windows Server 2012 R2 and Server Core installation (6.3.9600.0 before 6.3.9600.23470)
• Windows Server 2016 (10.0.14393.0 before 10.0.14393.9612)

Fixed in

• Windows 10 1607 and Windows Server 2016: 10.0.14393.9612
• Windows 10 1809: 10.0.17763.9376
• Windows 10 21H2: 10.0.19044.7807
• Windows 10 22H2: 10.0.19045.7807
• Windows 11 23H2: 10.0.22631.7652
• Windows 11 24H2: 10.0.26100.9711
• Windows 11 25H2: 10.0.26200.9711
• Windows 11 26H1: 10.0.28000.3231
• Windows 11 26H2: 10.0.26300.9711
• Windows Server 2012: 6.2.9200.26434
• Windows Server 2012 R2: 6.3.9600.23470

The corresponding KB numbers could not be verified; check the MSRC advisory.

Workaround

Unknown. No vendor workaround or mitigation was identified in the sources. Patching is the documented remedy.

Exploitation

• CISA SSVC in the CVE record: exploitation none, automatable no, technical impact total
• EPSS approximately 0.007
• No public proof of concept or in-the-wild exploitation was found in the sources.
• Whether this CVE is in the CISA KEV catalogue is unverified.

Our recommendation

• Identify all hosts with the NPS role, including Windows Server 2012 to 2016 and Windows 10 1607 systems.
• Install the October 2026 security update on affected systems, starting with servers exposed to untrusted networks.
• Restrict access to NPS (RADIUS) to required clients only and limit it to internal networks.
• Retire or upgrade Windows 10 1607 systems that are still in use.
• Check the MSRC advisory and the CISA KEV catalogue for updates.

Public exploits iAttack code is publicly available (PoC on GitHub, Metasploit or Exploit-DB).

PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.

Research sources

• Microsoft Security Update Guide: CVE-2026-85799 msrc.microsoft.com
• Vulners: MS:CVE-2026-85799 vulners.com
• Vulners: CVE-2026-85799 vulners.com
• OpenCVE: CVE-2026-85799 app.opencve.io
• Zero Day Initiative: October 2026 Security Update Review www.zerodayinitiative.com

Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 1 Nov 2026, 19:22.