Windows DWM Core Library: Local privilege escalation via out-of-bounds read
Summary
A flaw in the Windows DWM Core Library (Desktop Window Manager) allows an out-of-bounds read (CWE-125). An attacker with a valid local, low-privilege account can use it to elevate privileges to a higher level, with high impact on confidentiality, integrity and availability. The attack requires local access and no user interaction, so the risk is mainly on shared PCs, terminal servers and systems where malware already has a foothold.
Affected
- Windows 10 Version 1607 (10.0.14393.0 before 10.0.14393.9612)
- Windows 10 Version 1809 (10.0.17763.0 before 10.0.17763.9376)
- Windows 10 Version 21H2 (10.0.19044.0 before 10.0.19044.7807)
- Windows 10 Version 22H2 (10.0.19045.0 before 10.0.19045.7807)
- Windows 11 Version 23H2 (10.0.22631.0 before 10.0.22631.7652)
- Windows 11 Version 24H2 (10.0.26100.0 before 10.0.26100.9711)
- Windows 11 Version 25H2 (10.0.26200.0 before 10.0.26200.9711)
- Windows 11 Version 26H2 (10.0.26300.0 before 10.0.26300.9711)
- Windows Server 2016, including Server Core (10.0.14393.0 before 10.0.14393.9612)
- Windows Server 2019, including Server Core (10.0.17763.0 before 10.0.17763.9376)
- Windows Server 2022 (10.0.20348.0 before 10.0.20348.5761)
- Windows Server 2025 (10.0.26100.0 before 10.0.26100.33650)
Fixed in
- Install the Microsoft security update released on 13 October 2026 for the affected version.
- Fixed builds: 10.0.14393.9612 (1607 and Server 2016), 10.0.17763.9376 (1809 and Server 2019), 10.0.19044.7807 (21H2), 10.0.19045.7807 (22H2), 10.0.22631.7652 (23H2), 10.0.26100.9711 (24H2), 10.0.26200.9711 (25H2), 10.0.26300.9711 (26H2), 10.0.20348.5761 (Server 2022), 10.0.26100.33650 (Server 2025).
- KB number for Windows 10 1607: Unknown. Take it from the MSRC page or the Microsoft Update Catalog.
Workaround
Unknown. Microsoft lists no workaround; apply the update.
Exploitation
- Not known to be exploited in the wild.
- CISA SSVC: Exploitation none, Automatable no, Technical Impact total.
- Microsoft exploit maturity: Unproven. No public proof-of-concept found.
- EPSS below 1%.
Our recommendation
- Install the October 2026 Microsoft security update on all affected systems, with priority on shared PCs, terminal and RDS servers and kiosks.
- Restrict local accounts to least privilege.
- Check whether any Windows 10 1607 systems are still in use and verify their end-of-support date on the Microsoft lifecycle page before planning the upgrade.
- Monitor for suspicious local privilege changes and new processes on affected systems.
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)
- 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-2026-88177 msrc.microsoft.com
- Vulners: CVE-2026-88177 vulners.com
- OpenCVE: CVE-2026-88177 app.opencve.io
- Strix: CVE-2026-88177 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, 01:12.
Original description (NVD)
Out-of-bounds read 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.
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.