Windows Network Address Translation (NAT): Use-after-free enables remote code execution
Summary
A use-after-free flaw (CWE-416) in the Windows Network Address Translation (NAT) component allows an unauthenticated attacker to execute code over the network. The CVSS base score is 8.1, but attack complexity is rated high and no user interaction or credentials are needed. The main risk is for Windows hosts with the NAT function enabled and reachable from untrusted networks, such as servers acting as routers or internet gateways.
Affected
- Windows 10 Version 1607 (before 10.0.14393.9688)
- Windows 10 Version 1809 (before 10.0.17763.9487)
- Windows 10 Version 21H2 (before 10.0.19044.7846)
- Windows 10 Version 22H2 (before 10.0.19045.7846)
- Windows 11 Version 23H2 (before 10.0.22631.7711)
- Windows 11 Version 24H2 (before 10.0.26100.9974)
- Windows 11 Version 25H2 (before 10.0.26200.9974)
- Windows 11 Version 26H1 (before 10.0.28000.3501)
- Windows 11 Version 26H2 (before 10.0.26300.9974)
- Windows Server 2016 incl. Server Core (before 10.0.14393.9688)
- Windows Server 2019 incl. Server Core (before 10.0.17763.9487)
- Windows Server 2022 (before 10.0.20348.5870)
Fixed in
Fixed in the security update released on November 10, 2026. Install the build listed for your version or a later one (see the affected list).
Workaround
Unknown.
Exploitation
- No evidence of active exploitation found at publication.
- No public proof of concept found.
- Microsoft's exploitability index rates it "Exploitation More Likely" (forecast, not observed exploitation).
Our recommendation
- Patch affected Windows hosts as a priority, starting with internet-facing servers and gateways.
- Confirm whether the NAT function (for example via Routing and Remote Access) is actually needed; disable it where it is not.
- Block inbound access from untrusted networks to internal hosts on NAT-related ports.
- Replace unsupported systems such as Windows 10 1607 and 1809 or obtain extended support.
- Check the MSRC advisory for mitigations and monitor it for updates.
Information from Microsoft (Patch Tuesday November 2026)
- Severity (Microsoft)
- Critical
- Impact
- Remote code execution – Windows Network Address Translation (NAT)
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation more likely
- Product family
- Windows, Windows ESU (Extended Security Updates)
- Updates (KB)
- KB5131291, KB5131085, KB5131096, KB5131090, KB5131087, KB5132061
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide (MSRC) msrc.microsoft.com
- CVE.org CVE Record www.cve.org
- Tenable: Microsoft November 2026 Patch Tuesday www.tenable.com
- Qualys: Microsoft Patch Tuesday November 2026 review blog.qualys.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 11 Nov 2026, 01:45.
Original description (NVD)
Use after free in Windows Network Address Translation (NAT) allows an unauthorized attacker to execute code over a network.
NVD references (1)
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
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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