Microsoft Windows NTFS: Elevation of privilege via format string
Summary
A local attacker with an existing foothold on a Windows system can exploit an externally controlled format string flaw in the NTFS file system component to elevate privileges. The attacker needs valid low-privileged access, such as a user account or malware on the machine. The CVSS base score is 7.8 (High), and the flaw is not remotely exploitable from the internet.
Affected
- Windows 10 Version 1607 (10.0.14393.0 to before 10.0.14393.9612)
- Windows 10 Version 1809 (10.0.17763.0 to before 10.0.17763.9376)
- Windows 10 Version 21H2 (10.0.19044.0 to before 10.0.19044.7807)
- Windows 10 Version 22H2 (10.0.19045.0 to before 10.0.19045.7807)
- Windows 11 Versions 23H2, 24H2, 25H2, 26H1 and 26H2 (see MSRC for exact builds)
- Windows Server 2012, 2012 R2 and 2016 (including Server Core installations)
Fixed in
- Windows 10 1607: 10.0.14393.9612
- Windows 10 1809: 10.0.17763.9376
- Windows 10 21H2: 10.0.19044.7807
- Windows 10 22H2: 10.0.19045.7807
- Windows 11 23H2: 10.0.22631.7652
- Windows 11 24H2 and 25H2: 10.0.26100.9711 and 10.0.26200.9711
- Windows 11 26H1: 10.0.28000.3231
- Windows 11 26H2: 10.0.26300.9711
- Windows Server 2012 and 2012 R2: see MSRC for KB numbers
- Windows Server 2016: 10.0.14393.9612
KB article numbers: Unknown. Use the KB links on the MSRC page.
Workaround
- No vendor workaround found.
- Apply the Microsoft security update.
Exploitation
- Not listed in CISA KEV in the OpenCVE snapshot.
- CISA SSVC: exploitation none, not automatable.
- No public proof of concept found. This does not confirm that none exists.
- EPSS about 0.36%.
Our recommendation
- Inventory all Windows hosts by build number, with priority on Windows 10 1607 and 1809.
- Deploy the October 2026 cumulative update through the normal patch cycle, starting with multi-user systems, terminal servers and file servers.
- Check the Microsoft lifecycle page for 1607 and 1809 support status, and plan upgrades or ESU coverage for unsupported devices.
- Monitor for unusual privilege escalation activity and recheck CISA KEV periodically.
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 unlikely
- Product family
- Windows, Windows ESU (Extended Security Updates)
- Updates (KB)
- KB5127648, KB5126651, KB5126655, KB5126657, KB5126646, KB5126653
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-83585 msrc.microsoft.com
- NVD record via Vulners vulners.com
- CVE List record via Vulners vulners.com
- OpenCVE: CVE-2026-83585 app.opencve.io
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 2 Nov 2026, 03:35.
Original description (NVD)
Use of externally-controlled format string 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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