Windows 10 1809: Heap-based buffer overflow in Windows Kernel
Summary
A heap-based buffer overflow in the Windows Kernel affects Windows 10 version 1809 and Windows Server 2019. An authorized local attacker with a low-privilege account can exploit it to elevate privileges, potentially to SYSTEM. Exploitation requires local access and a valid account but no user interaction, and the flaw is not directly reachable from the internet.
Affected
- Microsoft Windows 10 Version 1809: builds 10.0.17763.0 to below 10.0.17763.9376
- Microsoft Windows Server 2019 (including Server Core): builds 10.0.17763.0 to below 10.0.17763.9376
- The CNA record lists further Windows versions with their own fixed builds; see the MSRC advisory.
Fixed in
- Build 10.0.17763.9376 or later (October 2026 security update)
- KB number: the Tenable plugin references KB5126651, not verified against Microsoft sources.
Workaround
Unknown. No workaround was found in the sources; install the update.
Exploitation
- No public proof of concept or exploitation in the wild was found in the sources. This is not confirmed absent.
- CISA SSVC: Exploitation none, Automatable no, Technical Impact total.
- EPSS 0.00341 (low modelled likelihood).
- CISA KEV status was not checked.
Our recommendation
- Inventory all Windows 10 1809 and Windows Server 2019 hosts.
- Install the October 2026 cumulative update, minimum build 10.0.17763.9376.
- Prioritise multi-user systems, terminal servers and servers; treat single-user desktops as medium.
- Plan an upgrade of 1809 systems, as this build is no longer current.
- Re-check the MSRC advisory and the CISA KEV catalog for changes.
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)
- KB5126651, KB5126655, KB5126657, KB5126646, KB5127648, KB5126653
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- MSRC Security Update Guide: CVE-2026-69898 msrc.microsoft.com
- Tenable plugin 365475 (Windows 10 1809 / Server 2019 update) www.tenable.com
- Tenable plugin 365465 www.tenable.com
- Vulners NVD record CVE-2026-69898 vulners.com
- Vulners Rapid7 record CVE-2026-69898 (EPSS) vulners.com
- Strix CVE record CVE-2026-69898 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, 04:47.
Original description (NVD)
Heap-based buffer overflow 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.
Affected? We can help.
We check whether your systems are affected, install updates and close the gap – continuously with the System Health Checker if you wish.