Microsoft Windows ICS: Heap-based buffer overflow allows local privilege escalation
Summary
A heap-based buffer overflow in the Windows Internet Connection Sharing (ICS) component allows an authorized local attacker to elevate privileges. The attacker needs local access and a low-privileged account, and the attack complexity is high. Successful exploitation could give the attacker high impact on confidentiality, integrity and availability of the system.
Affected
- Windows 10 Version 1607, 1809, 21H2, 22H2
- Windows 11 Version 23H2, 24H2, 25H2, 26H1, 26H2 (per CVE record; list to be verified)
- Windows Server 2016, 2019, 2022 (Server Core installations included)
- Exact affected build ranges: see the Microsoft advisory, as the CVE record and third-party sources differ.
Fixed in
- Fixed builds per the CVE record: Windows 10 1607 from 10.0.14393.9688; 1809 from 10.0.17763.9487; 21H2 from 10.0.19044.7846; 22H2 from 10.0.19045.7846; Windows 11 23H2 from 10.0.22631.7711; Server 2022 from 10.0.20348.5870.
- Unknown: complete fixed-build list for all versions; verify in the MSRC advisory.
Workaround
Unknown. No vendor workaround found in the accessible sources; check the MSRC advisory. Disabling ICS where it is not needed reduces exposure.
Exploitation
- CISA SSVC: exploitation none, not automatable, total technical impact.
- No evidence of in-the-wild exploitation, no CISA KEV entry and no public proof of concept found at the time of research.
Our recommendation
- Deploy the Microsoft cumulative update for affected Windows versions via WSUS, Intune or your RMM, prioritizing multi-user PCs and servers.
- Verify the fixed builds against the MSRC advisory before closing the ticket.
- Disable Internet Connection Sharing where it is not required.
- Restrict local interactive logons on shared machines and terminal servers.
Information from Microsoft (Patch Tuesday November 2026)
- Severity (Microsoft)
- Important
- Impact
- Elevation of privilege – Windows Internet Connection Sharing (ICS)
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation less 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: CVE-2026-122179 msrc.microsoft.com
- CVE Record CVE-2026-122179 www.cve.org
- Strix.ai: CVE-2026-122179 www.strix.ai
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, 08:22.
Original description (NVD)
Heap-based buffer overflow in Windows Internet Connection Sharing (ICS) allows an authorized attacker to elevate privileges locally.
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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