Windows DWM Core Library: Use-after-free allows local privilege escalation
Summary
The Windows Desktop Window Manager (DWM) Core Library contains a use-after-free vulnerability (CWE-416). An authorized local user with low privileges can exploit it to elevate privileges, potentially to full system control. Remote exploitation is not possible, and the CVSS base score is 7.8 (High).
Affected
- Windows 10 Version 1607 and Windows Server 2016 (including Server Core): below 10.0.14393.9612
- Windows 10 Version 1809 and Windows Server 2019 (including Server Core): below 10.0.17763.9376
- Windows 10 Version 21H2 and 22H2: below 10.0.19044.7807 and 10.0.19045.7807
- Windows Server 2022: below 10.0.20348.5761
- Windows 11 Versions 23H2, 24H2, 25H2, 26H1 and 26H2: see the Microsoft advisory for exact builds
Fixed in
- October 2026 security update from Microsoft.
- Windows 10 1607 and Server 2016: build 10.0.14393.9612 or later.
- The KB number for Windows 10 1607 is unknown; check the Microsoft Security Update Guide.
Workaround
Unknown.
Exploitation
- No evidence of exploitation in the wild found.
- CISA SSVC: Exploitation none, Automatable no.
- No public proof of concept found in research; this does not rule out that one exists.
- EPSS about 0.3%.
Our recommendation
- Inventory Windows 10 1607 and Server 2016 hosts, prioritizing multi-user, kiosk and line-of-business systems.
- Install the October 2026 update and verify the build is 10.0.14393.9612 or later.
- Check whether legacy systems still receive security updates; isolate or replace unsupported systems.
- Restrict local logon and interactive sessions on unpatched hosts, and monitor for privilege escalation activity.
Information from Microsoft (Patch Tuesday October 2026)
- Severity (Microsoft)
- Important
- Impact
- Elevation of privilege – Windows DWM Core Library
- 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-2026-83726 msrc.microsoft.com
- NVD record via Vulners vulners.com
- Microsoft CNA record via Vulners vulners.com
- CVE list record via Vulners vulners.com
- OpenCVE: CVE-2026-83726 app.opencve.io
- Strix: CVE-2026-83726 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, 03:14.
Original description (NVD)
Use after free in Windows DWM Core Library 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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