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Microsoft Windows NAT: Use-after-free leads to remote code execution

CVE-2026-88212High 7.5

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Summary

A use-after-free vulnerability (CWE-416) in the Windows Network Address Translation (NAT) component allows an unauthorized attacker to execute code. The attacker must be on the same adjacent network segment, and exploitation is rated high complexity. No privileges or user interaction are required.

Affected

  • Windows 10 Version 1607: 10.0.14393.0 to before 10.0.14393.9688
  • Windows 10 Version 1809: 10.0.17763.0 to before 10.0.17763.9487
  • Windows 10 Version 21H2: 10.0.19044.0 to before 10.0.19044.7846
  • Windows 10 Version 22H2: 10.0.19045.0 to before 10.0.19045.7846
  • Windows 11 Version 23H2: 10.0.22631.0 to before 10.0.22631.7711
  • Windows 11 Version 24H2: 10.0.26100.0 to before 10.0.26100.9974
  • Windows 11 Version 25H2: 10.0.26200.0 to before 10.0.26200.9974
  • Windows 11 Version 26H1: 10.0.28000.0 to before 10.0.28000.3501
  • Windows 11 Version 26H2: 10.0.26300.0 to before 10.0.26300.9974
  • Windows Server 2016 (including Server Core): 10.0.14393.0 to before 10.0.14393.9688
  • Windows Server 2019 (including Server Core): 10.0.17763.0 to before 10.0.17763.9487
  • Windows Server 2022: 10.0.20348.0 to before 10.0.20348.5870
  • Version ranges taken from the CVE record; not yet verified against the MSRC entry.

Fixed in

  • Install the November 2026 security updates for the affected Windows versions (builds at or above the fixed values listed above).
  • The KB numbers for this CVE are unknown.

Workaround

  • No documented workaround.
  • Unverified: if the NAT or Internet Connection Sharing role is not needed, disabling it reduces exposure. Confirm with MSRC before relying on this.

Exploitation

  • CISA SSVC: exploitation none, not automatable, total technical impact.
  • No public exploitation or proof-of-concept known for this CVE at the time of research.
  • NVD analysis pending.

Our recommendation

  • Inventory Windows hosts and identify any that run NAT or Internet Connection Sharing, for example as a makeshift router or gateway.
  • Patch affected systems in the November 2026 update cycle, prioritizing these gateway hosts.
  • Where NAT is not required, disable the role.
  • Restrict untrusted devices and guest Wi-Fi from reaching the local network segment.
  • Check the MSRC entry for exact fixed builds and monitor for exploitation updates.

Information from Microsoft (Patch Tuesday November 2026)

Severity (Microsoft)
Important
Impact
Remote code execution – Windows Network Address Translation (NAT)
Status on Patch Tuesday
Neither exploited nor publicly disclosed
Exploitability assessment
Exploitation unlikely
Product family
Windows, Windows ESU (Extended Security Updates)
Updates (KB)
KB5131291, KB5131085, KB5131096, KB5131090, KB5131087, KB5132061

Entry in the Microsoft Security Update Guide

Public exploits

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

Research sources

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 11 Nov 2026, 05:08.

Original description (NVD)

Use after free in Windows Network Address Translation (NAT) allows an unauthorized attacker to execute code over an adjacent network.

NVD references (1)

Sources

The tracker combines official, freely usable data sources – updated continuously:

This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.

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