Windows 10 1607 NTFS: Race condition allows local privilege escalation
Summary
A race condition in the NTFS file system component of Windows 10 Version 1607 allows an authorized local user to elevate privileges. The attack complexity is high and low privileges are required, but no user interaction is needed. The flaw is not reachable from the internet and is mainly a step after an attacker or malware already has a user foothold on the device.
Affected
- Microsoft Windows 10 Version 1607: builds 10.0.14393.0 to below 10.0.14393.9612
- Microsoft Windows Server 2016: builds 10.0.14393.0 to below 10.0.14393.9612 (same range as listed in the CNA record)
Fixed in
- Windows 10 Version 1607: 10.0.14393.9612 or later (per CNA and NVD mirrors; confirm on the MSRC advisory)
- KB number for Version 1607: Unknown.
Workaround
- No vendor workaround known.
- Limit local accounts and services that perform NTFS operations to least privilege. This reduces impact but does not fix the flaw.
Exploitation
- Not listed in CISA KEV.
- CISA SSVC data: exploitation none, automatable no, technical impact total.
- EPSS 0.00241 (below 1%).
- VulDB reports no exploit available. No public proof of concept or in-the-wild reports found; this is not proof that none exists.
Our recommendation
- Check whether any devices still run Windows 10 Version 1607, such as kiosks, POS systems, thin clients or HMIs.
- Migrate these devices to a supported Windows version, or enrol them in Extended Security Updates if migration is not possible.
- Ask Microsoft Volume Licensing or your CSP whether the fix for 1607 is available only through ESU.
- Apply the fixed build 10.0.14393.9612 or later after confirming it on the MSRC advisory.
- Restrict local logons and service accounts on affected devices to the minimum required.
Information from Microsoft (Patch Tuesday October 2026)
- Severity (Microsoft)
- Important
- Impact
- Elevation of privilege – Windows NTFS
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation more likely
- Product family
- Windows, Windows ESU (Extended Security Updates)
- Updates (KB)
- KB5126651, KB5126655, KB5126657, KB5126646, KB5127648, KB5126653
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-81971 msrc.microsoft.com
- Vulners: CNA record CVE-2026-81971 vulners.com
- Vulners: NVD record CVE-2026-81971 vulners.com
- OpenCVE: CVE-2026-81971 app.opencve.io
- VulDB: entry 418786 vuldb.com
- Strix: CVE-2026-81971 www.strix.ai
- 4sysops: Windows 10 Enterprise LTSB 2016 end of support and ESU 4sysops.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 4 Nov 2026, 08:47.
Original description (NVD)
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows NTFS 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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