Microsoft Windows 10 1607: Use-after-free in kernel allows privilege escalation
Summary
A use-after-free flaw (CWE-416) in the Windows kernel of Windows 10 Version 1607 allows a local attacker to elevate privileges. The attacker needs a low-privilege account on the system. Windows Server 2016 uses the same affected build range according to the official CVE record. The CVSS base score is 7.8 (HIGH).
Affected
- Windows 10 Version 1607: builds 10.0.14393.0 to before 10.0.14393.9612
- Windows Server 2016 (including Server Core): builds 10.0.14393.0 to before 10.0.14393.9612
- Microsoft does not state which kernel component is affected.
Fixed in
- Build 10.0.14393.9612 or later.
- KB5126868 (Oct 13, 2026) is believed to install build 14393.9612. This link is an inference from the build number and must be confirmed on the MSRC page.
- KB5134123 (out-of-band, non-security, cumulative, Oct 26, 2026) installs build 14393.9615.
Workaround
Unknown. No vendor-documented workaround was found.
Exploitation
- CISA SSVC: Exploitation none, Automatable no.
- The CVSS temporal values are E:U (unproven exploit code) and RC:C (confirmed).
- EPSS score: 0.00318.
- No public proof of concept, exploitation in the wild or CISA KEV listing was found as of this assessment.
Our recommendation
- Inventory all Windows 10 1607 and Windows Server 2016 systems.
- Install build 10.0.14393.9612 or later, preferably KB5134123, after confirming the KB on the MSRC page.
- Check whether Extended Security Updates are available for 1607. Microsoft has ended updates for this release, so October 2026 may be the last security update.
- Plan migration to a supported Windows version.
- Monitor for public exploit code, because this flaw is only exploitable after an attacker already has code running on the host.
Information from Microsoft (Patch Tuesday October 2026)
- Severity (Microsoft)
- Important
- Impact
- Elevation of privilege – Windows Kernel
- 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-2026-88134 msrc.microsoft.com
- Vulners: CVE-2026-88134 vulners.com
- OpenCVE: CVE-2026-88134 app.opencve.io
- Microsoft Support: KB5134123 Windows 10 1607 update support.microsoft.com
- Microsoft Learn: Windows 10 1607 and Server 2016 release health learn.microsoft.com
- Strix.ai: CVE-2026-88134 www.strix.ai
- ManageEngine Patch Tuesday October 2026 pitstop.manageengine.com
- KACE Patch Tuesday changelog 2026-10-15 changelog.kace.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 2 Nov 2026, 01:17.
Original description (NVD)
Use after free in Windows Kernel 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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