Microsoft Windows 10 1607: Local privilege escalation in WSUS component
Summary
A flaw in a Windows Server Update Service (WSUS) component of Windows 10 Version 1607 and Windows Server 2016 (build 14393) allows an authorized local user to gain higher privileges. The attacker needs a valid low-privileged account on the system, and the CVSS vector does not assume network access. The advisory does not state whether the flaw affects only the WSUS server role or also client systems.
Affected
- Windows 10 Version 1607 (x86 and x64): builds below 10.0.14393.9612
- Windows Server 2016 and Server Core installation: builds below 10.0.14393.9612
- Windows 10 Version 1809: builds below 10.0.17763.9376
- Windows Server 2019 and Server Core installation: builds below 10.0.17763.9376
- Windows Server 2012 and Server Core installation: builds below 6.2.9200.26434
- Windows Server 2012 R2 and Server Core installation: builds below 6.3.9600.23470
- Windows Server 2022: builds below 10.0.20348.5761
- Windows Server 2025 and Server Core installation: builds below 10.0.26100.33650
Fixed in
- Windows 10 1607 and Windows Server 2016: build 10.0.14393.9612 or later, delivered by KB5126868 (October 13, 2026)
- Later October 2026 update KB5134123 (build 14393.9615) for Windows 10 1607 (not verified against the advisory wording)
- Other listed products: fixed builds as given in the affected ranges (not individually verified)
Workaround
Unknown. No vendor workaround was found. A third-party source advises enforcing least privilege on local accounts that could use the update service, but this is not vendor guidance.
Exploitation
- Microsoft rates exploit code maturity as Unproven
- CISA SSVC: exploitation none, automatable no, technical impact total
- Not listed in CISA KEV at the time of research
- No public proof of concept or in-the-wild exploitation found; this does not prove none exists
Our recommendation
- Identify all Windows 10 1607 and Windows Server 2016 systems (build 14393) and check whether the WSUS role is installed
- Install KB5126868 or the later October 2026 update, then confirm the build is at least 10.0.14393.9612
- Review local accounts and WSUS administrator rights
- Plan migration off Windows 10 1607 (LTSB 2016, out of updates as of October 13, 2026) and Windows Server 2016 (extended support ends January 12, 2027)
- Monitor CISA KEV and public exploit sources for changes
Information from Microsoft (Patch Tuesday October 2026)
- Severity (Microsoft)
- Important
- Impact
- Elevation of privilege – Windows Server Update 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)
- KB5126651, KB5126655, KB5126646, KB5126868, KB5126835, KB5126836
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Microsoft Security Update Guide: CVE-2026-83499 msrc.microsoft.com
- KB5126868: Windows 10 1607 security update support.microsoft.com
- Windows 10 1607 and Windows Server 2016 release health status learn.microsoft.com
- CVE record via Vulners (CVELIST) vulners.com
- NVD record via Vulners vulners.com
- OpenCVE CVE-2026-83499 (third-party) app.opencve.io
- Windows Server 2016 (Wikipedia) en.wikipedia.org
- Windows 10 version history (Wikipedia) en.wikipedia.org
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, 03:43.
Original description (NVD)
Insufficient granularity of access control in Windows Server Update 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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