Windows DWM Core Library: Heap-based buffer overflow enables local privilege escalation

Summary

The Windows DWM Core Library, the desktop compositing component of Windows, contains a heap-based buffer overflow (CWE-122). A local user with low privileges can exploit it to elevate privileges on the affected system. No user interaction is required, and successful exploitation can fully compromise confidentiality, integrity and availability of the host.

Affected

• Windows 10 Version 1809 and Windows Server 2019 (including Server Core): builds 10.0.17763.0 to below 10.0.17763.9376
• Windows 10 Version 21H2: builds 10.0.19044.0 to below 10.0.19044.7807
• Windows 10 Version 22H2: builds 10.0.19045.0 to below the fixed build (exact value unclear, see fixed)
• Windows 11 Version 23H2: builds 10.0.22631.0 to below 10.0.22631.7652
• Windows 11 Version 24H2: builds 10.0.26100.0 to below 10.0.26100.9711
• Windows 11 Version 25H2 and 26H2: builds below 10.0.26200.9711 and 10.0.26300.9711
• Windows 11 Version 26H1: builds below 10.0.28000.3231
• Windows Server 2022: builds below 10.0.20348.5761
• Windows Server 2025 (including Server Core): builds below 10.0.26100.33650

Fixed in

• Windows 10 Version 1809 and Windows Server 2019: 10.0.17763.9376 or later (a mirror lists KB5126651, unverified)
• Windows 10 Version 21H2: 10.0.19044.7807 or later
• Windows 10 Version 22H2: Unknown. The published range is inconsistent; confirm the build with Microsoft
• Windows 11 Version 23H2: 10.0.22631.7652 or later
• Windows 11 Version 24H2: 10.0.26100.9711 or later
• Windows 11 Version 25H2 and 26H2: 10.0.26200.9711 or later and 10.0.26300.9711 or later
• Windows 11 Version 26H1: 10.0.28000.3231 or later
• Windows Server 2022: 10.0.20348.5761 or later
• Windows Server 2025: 10.0.26100.33650 or later

Workaround

• Unknown. No Microsoft workaround was found; the security update is the primary remediation.

Exploitation

• No evidence of exploitation in the wild found.
• Not listed in the CISA KEV catalog.
• CISA SSVC: Exploitation none, Automatable no, Technical Impact total.
• No public proof-of-concept exploit found.
• EPSS values differ between sources (0.00318 and 0.35%).

Our recommendation

• Install the October 2026 security update on all affected Windows systems; confirm the KB number and the Windows 10 22H2 build in the Microsoft Security Update Guide first.
• Limit interactive and remote desktop logons on multi-user hosts and remove unneeded local accounts.
• Keep endpoint detection and response (EDR) active and monitor for signs of privilege escalation.
• Re-check the NVD status, as sources show conflicting values.

Public exploits iAttack code is publicly available (PoC on GitHub, Metasploit or Exploit-DB).

PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.

Research sources

• Microsoft Security Update Guide: CVE-2026-88128 msrc.microsoft.com
• Vulners CVE List record (CNA data) vulners.com
• OpenCVE: CVE-2026-88128 app.opencve.io
• Vulners Vulnrichment record (CISA SSVC) vulners.com
• Strix: CVE-2026-88128 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, 01:23.