Microsoft Windows 10 1607: Use after free in Clipboard User Service allows privilege escalation
Summary
A use-after-free flaw in the Windows Clipboard User Service allows an authorized local attacker to elevate privileges. Microsoft rates the attack complexity as high and the user interaction as none, and says an attacker could raise privileges from low to medium integrity level. Windows 10 Version 1607 and Windows Server 2016 are affected; attackers need local access and low privileges, so the risk is mainly for shared systems or hosts where malware or a phished user already has a foothold.
Affected
- Windows 10 Version 1607 before build 10.0.14393.9612
- Windows Server 2016 (including Server Core) before build 10.0.14393.9612
- Other Windows 10, Windows 11 and Windows Server versions are listed as affected in the CVE record with their own fixed builds.
Fixed in
- Security update for Windows 10 Version 1607 and Windows Server 2016 that brings the build to 10.0.14393.9612 or later (KB number: unknown, check the MSRC update guide).
Workaround
Unknown. No workaround was found in the sources reviewed; the security update is the fix.
Exploitation
- Microsoft lists the vulnerability as not exploited and exploit code maturity as unproven.
- CISA SSVC: exploitation none, automatable no, technical impact total.
- Not in the CISA KEV list; EPSS below 1%.
- No public proof of concept found in the research; this does not rule out that one exists.
Our recommendation
- Identify all Windows 10 1607 and Windows Server 2016 systems and check whether they are still supported by Microsoft.
- Install the October 2026 security update from the MSRC update guide as soon as possible; confirm the KB for your build there.
- If the systems cannot be patched, plan a replacement or upgrade to a supported Windows version and restrict local logons on multi-user hosts and terminal servers.
- Monitor for unusual privilege changes on shared and remote desktop systems.
Information from Microsoft (Patch Tuesday October 2026)
- Severity (Microsoft)
- Important
- Impact
- Elevation of privilege – Windows Clipboard User 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, 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-2026-85863 msrc.microsoft.com
- OpenCVE: CVE-2026-85863 app.opencve.io
- Vulners Microsoft mirror: MS:CVE-2026-85863 vulners.com
- Vulners NVD: CVE-2026-85863 vulners.com
- Strix: CVE-2026-85863 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, 01:53.
Original description (NVD)
Use after free in Windows Clipboard User 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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