EUVD-2026-43859
GHSA-c6c5-jmx4-j33p
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local kernel EoP requiring a low-privileged authenticated session (AV:L, PR:L), no user interaction, and yielding full SYSTEM-level C/I/A impact.
Primary rating from Vendor (microsoft).
CVSS VectorNVD
Lifecycle Timeline
5DescriptionNVD
Use after free in Windows Kernel-Mode Drivers allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in Windows Kernel-Mode Drivers on Windows 11 (24H2, 25H2, 26H1) and Windows Server 2025 allows an authenticated low-privileged attacker to gain SYSTEM-level control by exploiting a use-after-free (CWE-416) memory-corruption condition. Microsoft has published a patch, and no public exploit has been identified at time of analysis; EPSS is low at 0.20% (10th percentile) and CISA SSVC records exploitation as none, though the technical impact is rated total. Successful exploitation grants full confidentiality, integrity, and availability compromise of the affected host.
Technical ContextAI
The flaw resides in Windows Kernel-Mode Drivers, code that executes in ring-0 and mediates hardware and core OS services; a use-after-free (CWE-416) occurs when the driver continues to reference kernel object memory after it has been freed, allowing an attacker who can control the reallocated memory to corrupt kernel state. The CPE data scopes this to Microsoft Windows 11 versions 24H2, 25H2, and 26H1, plus Windows Server 2025 including the Server Core installation. Because the vulnerable code runs in kernel mode, a successful reallocation-and-reuse primitive can be leveraged to overwrite function pointers or object headers and redirect execution or escalate the calling thread's token, which is why the technical impact is assessed as total. The associated tags also note denial-of-service potential, consistent with the instability inherent in use-after-free conditions.
RemediationAI
Apply the Microsoft cumulative update that raises the affected component to or above the fixed build for your platform - Vendor-released patch: 10.0.26100.8875 (Windows 11 24H2), 10.0.26200.8875 (Windows 11 25H2), 10.0.28000.2269 (Windows 11 26H1), and 10.0.26100.33158 (Windows Server 2025 and its Server Core installation) - per Microsoft's advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50393. Because exploitation requires an authenticated local session, effective compensating controls until patching completes include restricting interactive and local logon rights to trusted administrators, enforcing least privilege to keep standard users off sensitive servers, and enabling attack-surface-reduction and exploit-protection kernel mitigations; note these controls reduce but do not eliminate risk since any low-privileged foothold satisfies the PR:L precondition, and aggressive logon restrictions can disrupt legitimate service accounts. There is no vendor-documented feature toggle to disable the affected kernel driver, so patching is the only complete fix.
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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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