EUVD-2026-44256
GHSA-2wqv-j5pw-q5fx
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local privilege escalation requires prior low-privileged code execution (AV:L, PR:L) with no user interaction; kernel-mode compromise yields full C/I/A impact within the unchanged local scope.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Use after free in Windows Kernel allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in the Microsoft Windows Kernel allows an authenticated attacker to elevate to SYSTEM by exploiting a use-after-free (CWE-416) memory corruption condition, spanning Windows 10 (1607 through 22H2), Windows 11 (24H2/25H2/26H1), and Windows Server 2016 through 2025. Reported by Microsoft with a CVSS 3.1 base score of 7.8 (AV:L/AC:L/PR:L/UI:N), the flaw grants full confidentiality, integrity, and availability impact on the local system. No public exploit identified at time of analysis, and it is not listed in CISA KEV; a vendor patch is available.
Technical ContextAI
The vulnerability resides in the core Windows Kernel (ntoskrnl-level code), the trusted component that mediates all process scheduling, memory management, and hardware access at the highest privilege ring. The root cause is CWE-416 (Use After Free): a kernel object is freed while a dangling reference remains, and subsequent dereference of that stale pointer lets an attacker manipulate freed-then-reallocated memory. Because the affected code executes in kernel mode, successful control of the freed allocation can be groomed into an arbitrary read/write or controlled-execution primitive. The CPE set confirms the affected surface is the base OS across the Windows 10, Windows 11, and Windows Server product families (client versions 1607-26H1 and Server 2016-2025), not an add-on application, indicating a defect in a shared kernel code path present across supported builds.
RemediationAI
Apply the Microsoft cumulative security update that addresses CVE-2026-56644 for each affected build; the exact fixed build numbers are enumerated per product on the MSRC advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56644 (Patch available per vendor advisory - install the latest monthly cumulative update for your Windows 10, Windows 11, or Windows Server version). Because this is a kernel defect with no configuration toggle, there is no supported feature-level workaround; where immediate patching is not possible, reduce exposure by enforcing least-privilege so fewer local accounts can run code, restricting interactive and remote-desktop logon rights on servers, and deploying kernel-exploit mitigations such as HVCI/Hypervisor-Enforced Code Integrity and Attack Surface Reduction rules to raise the cost of exploitation - noting these controls only lower likelihood and do not remove the vulnerable code, and HVCI can affect compatibility with unsigned or older drivers. Prioritize patching on multi-user, jump-box, and terminal-server systems where untrusted local code is most likely to run.
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Same weakness CWE-416 – Use After Free
View allSame technique Use After Free
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External POC / Exploit Code
Leaving vuln.today