EUVD-2026-56668
GHSA-wwfh-hmvc-m8r5
Severity by source
AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Local-only vector with race-condition complexity requires a pre-existing low-privilege foothold; full C/I/A impact reflects kernel-level SYSTEM control with no scope change.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
3DescriptionCVE.org
Use after free in Windows Kernel allows an authorized attacker to elevate privileges locally.
AnalysisAI
Privilege escalation via use-after-free in the Windows Kernel affects Windows 11 (versions 23H2, 24H2, 25H2, and 26H1) and Windows Server 2025, enabling a locally authenticated low-privileged attacker to elevate to SYSTEM-level control. The CWE-416 root cause combined with high attack complexity (AC:H) indicates exploitation likely requires precise timing or race-condition engineering rather than a trivial one-shot trigger. Vendor patches are available via MSRC; no active exploitation has been confirmed by CISA KEV at time of analysis.
Technical ContextAI
The Windows Kernel is the core privileged component of Microsoft Windows responsible for memory management, process scheduling, hardware abstraction, and system call handling. CWE-416 (Use After Free) describes a memory safety flaw where a heap or kernel-pool object is freed while one or more pointers to it remain valid; a subsequent dereference of that dangling pointer - particularly under attacker-controlled timing - can corrupt adjacent kernel memory, hijack function pointers, or redirect execution into attacker-supplied shellcode. Kernel-space use-after-free vulnerabilities are especially critical because successful exploitation bypasses all user-mode privilege boundaries and achieves the highest privilege level on the system. The tags 'Memory Corruption' and 'Denial Of Service' from EUVD-2026-56668 indicate the flaw may manifest as either privilege escalation or a kernel crash (BSOD), depending on exploit precision. Affected platforms per EUVD version data include Windows 11 build families 22631, 26100, 26200, and 28000, as well as Windows Server 2025 in both standard and Server Core configurations.
RemediationAI
Apply the vendor-released patch via Windows Update, Windows Server Update Services (WSUS), or Microsoft Update Catalog, targeting the following minimum fixed build versions confirmed by EUVD-2026-56668: 10.0.22631.7517 or later for Windows 11 23H2, 10.0.26100.9168 or later for Windows 11 24H2 and Windows Server 2025 (including Server Core), 10.0.26200.9168 or later for Windows 11 25H2, 10.0.28000.2704 or later for Windows 11 26H1, and 10.0.26100.33296 or later for Windows Server 2025 standard and Server Core installations. Full advisory details are at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-62788. Where immediate patching is not feasible, enforce strict least-privilege access controls by auditing and removing unnecessary local accounts and service accounts - this does not eliminate the vulnerability but reduces the pool of principals that could trigger it after establishing a foothold via another vector. Note that restricting interactive local logon via Group Policy (e.g., 'Deny log on locally' for non-essential accounts) limits lateral movement but does not protect systems where the attacker already has remote code execution through another channel. The Denial of Service tag suggests unpatched systems also face kernel crash risk from failed exploit attempts, adding an availability argument for prioritizing this patch.
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Same weakness CWE-416 – Use After Free
View allSame technique Denial Of Service
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External POC / Exploit Code
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