Windows TCP/IP: Use-after-free allows code execution from adjacent network
Summary
A use-after-free flaw in the Windows TCP/IP stack allows an unauthenticated attacker on an adjacent network to execute code. Microsoft rates the CVSS base score at 7.5 (High) and its maximum severity as Critical. The attack requires high complexity and conditions beyond the attacker's control, so it is not directly reachable from the internet.
Affected
- Windows 11 Version 24H2 (10.0.26100.0 before 10.0.26100.9974)
- Windows 11 Version 25H2 (10.0.26200.0 before 10.0.26200.9974)
- Windows 11 Version 26H1 (10.0.28000.0 before 10.0.28000.3501)
- Windows 11 Version 26H2 (10.0.26300.0 before 10.0.26300.9974)
- Windows Server 2025, including Server Core (10.0.26100.0 before 10.0.26100.33822)
- Windows 10 and Windows Server 2019/2022: not listed in the sources reviewed; check the MSRC product list
Fixed in
- Windows 11 24H2: 10.0.26100.9974 or later
- Windows 11 25H2: 10.0.26200.9974 or later
- Windows 11 26H1: 10.0.28000.3501 or later
- Windows 11 26H2: 10.0.26300.9974 or later
- Windows Server 2025: 10.0.26100.33822 or later
Exact KB numbers: Unknown.
Workaround
Unknown. No vendor-documented workaround was found; applying the security update is the available remedy.
Exploitation
- Microsoft's CVSS temporal vector (E:U) reports no known exploit code.
- CISA SSVC: exploitation none, automatable no, technical impact total.
- Public proof of concept: Unknown.
- The Outlook flaw that Microsoft reports as exploited in the wild is a different CVE.
Our recommendation
- Install the November 2026 cumulative update on all affected Windows 11 and Windows Server 2025 systems, starting with servers and hosts on shared network segments.
- Check that the separate Outlook/Office fix for the exploited flaw is also deployed.
- Reduce exposure until patching is complete by limiting access to flat LANs, shared guest or IoT Wi-Fi, and untrusted hosts on the same segment.
- Monitor for unusual network activity on affected hosts.
Information from Microsoft (Patch Tuesday November 2026)
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- MSRC Security Update Guide msrc.microsoft.com
- CVE.org record www.cve.org
- Talos: Microsoft Patch Tuesday November 2026 blog.talosintelligence.com
- Splashtop: Patch Tuesday November 2026 www.splashtop.com
- Zero Day Initiative: November 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 11 Nov 2026, 05:52.
Original description (NVD)
Use after free in Windows TCP/IP 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:
- 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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