EUVD-2026-56405
GHSA-35mh-m2vc-vgv8
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local vector and low-privilege requirement confirmed by description; full C/I/A reflects achievable SYSTEM-level privilege escalation with no scope change.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
3DescriptionCVE.org
Heap-based buffer overflow in Windows DWM Core Library allows an authorized attacker to elevate privileges locally.
AnalysisAI
Privilege escalation via heap-based buffer overflow in the Windows Desktop Window Manager (DWM) Core Library affects a broad range of Windows client and server editions spanning from Windows 10 1607 through Windows 11 26H1 and multiple Windows Server releases. An authenticated local attacker can exploit the overflow to gain full system-level privileges, achieving high confidentiality, integrity, and availability impact on the compromised host. No public exploit has been identified at time of analysis, and no active exploitation has been confirmed by CISA KEV, but the vendor has released patches addressing the affected builds.
Technical ContextAI
The Desktop Window Manager (dwm.exe) is a compositing window manager integral to Windows visual rendering, handling GPU-accelerated window composition for all graphical sessions. CWE-122 (Heap-based Buffer Overflow) indicates that the vulnerability resides in dynamic memory allocation logic within the DWM Core Library - likely a scenario where an attacker-controlled value drives a write operation that exceeds the bounds of a heap-allocated buffer, enabling controlled corruption of adjacent heap memory. This class of vulnerability in a high-privilege graphical subsystem is a well-understood local privilege escalation path: DWM runs in a privileged context, and corrupting its heap can redirect execution to attacker-controlled code or data. Affected CPEs span Windows 10 builds (1607/21H2/22H2/1809) and Windows 11 builds (23H2/24H2/25H2/26H1), as well as Windows Server 2016, 2019, 2022, and 2025, both standard and Server Core installations.
RemediationAI
The primary remediation is to apply the vendor-released patch via Windows Update or WSUS targeting the fixed build numbers per affected version: Windows 10 1607/Server 2016 to build 10.0.14393.9418 or later, Windows 10 1809/Server 2019 to build 10.0.17763.9115 or later, Windows 10 21H2 to build 10.0.19044.7663 or later, Windows 10 22H2 to build 10.0.19045.7663 or later, Windows 11 23H2 to build 10.0.22631.7517 or later, Windows 11 24H2/Server 2025 to build 10.0.26100.9168 or later (note: Server 2025 requires 10.0.26100.33296), Windows 11 25H2 to build 10.0.26200.9168 or later, Windows 11 26H1 to build 10.0.28000.2704 or later, and Windows Server 2022 to build 10.0.20348.5499 or later. The full advisory is published at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-62894. Where immediate patching is infeasible, compensating controls should focus on limiting local code execution by untrusted users: enforce application allowlisting via AppLocker or WDAC to prevent arbitrary process execution, restrict interactive logon rights to only necessary accounts via Group Policy (User Rights Assignment), and monitor DWM crash events (Event ID 1000/1001 in Application log) as a potential indicator of exploitation attempts. These controls reduce the attack surface but do not eliminate the vulnerability - patching remains the only definitive fix.
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Same weakness CWE-122 – Heap-based Buffer Overflow
View allSame technique Buffer Overflow
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External POC / Exploit Code
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