Microsoft Windows 10 1607: Link following in Windows User Profile Service
Summary
A link following flaw (CWE-59) in the Windows User Profile Service allows an authorized local user to elevate privileges. The service runs at SYSTEM level and handles per-user profile loading. Exploitation requires a valid local account and is not possible remotely, so the risk mainly concerns footholds such as phished users, malware or rogue employees, and is higher on shared or multi-user systems.
Affected
- Windows 10 Version 1607 (build 10.0.14393.0 to below 10.0.14393.9612)
- Windows Server 2016 (build 10.0.14393.0 to below 10.0.14393.9612)
- Other Windows 10, Windows 11 and Windows Server versions are also listed in the CNA record; check the MSRC advisory for the complete list.
Fixed in
- Windows 10 Version 1607 and Windows Server 2016: build 10.0.14393.9612 or later (KB5126868, October 13, 2026)
- Verify the fixed build for other versions on the MSRC advisory.
Workaround
Unknown.
Exploitation
- Not listed in the CISA KEV catalog.
- CISA SSVC data: exploitation none, automatable no, technical impact total.
- EPSS score 0.00341 (below 1%).
Our recommendation
- Inventory all Windows 10 1607 and Windows Server 2016 systems and confirm they run build 14393.9612 or later.
- Install the October 2026 security update (KB5126868) on these systems; if 1607 is no longer eligible for updates on a device, plan its replacement.
- Prioritize shared PCs, terminal servers and file servers with many local accounts.
- Monitor for unexpected privilege changes and new SYSTEM-level processes on affected hosts.
- Priority for most SMEs: medium; raise to high if affected systems are shared or an attacker may already have a foothold.
Information from Microsoft (Patch Tuesday October 2026)
- Severity (Microsoft)
- Important
- Impact
- Elevation of privilege – Windows User Profile Service
- Status on Patch Tuesday
- Neither exploited nor publicly disclosed
- Exploitability assessment
- Exploitation less likely
- 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-2026-83659 msrc.microsoft.com
- Microsoft KB5126868 Windows 10 1607 security update support.microsoft.com
- Tenable plugin 365471 (KB5126868) www.tenable.com
- Microsoft release health: resolved issues Windows 10 1607 learn.microsoft.com
- Vulners NVD record CVE-2026-83659 vulners.com
- OpenCVE CVE-2026-83659 app.opencve.io
- Strix CVE-2026-83659 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 2 Nov 2026, 03:25.
Original description (NVD)
Improper link resolution before file access ('link following') in Windows User Profile Service 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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