EUVD-2026-43849
GHSA-9jwx-qjpv-cfrv
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local vector and low-privilege foothold required (AV:L/PR:L) for a kernel EoP; low complexity with no UI, yielding full SYSTEM compromise (C:H/I:H/A:H).
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Heap-based buffer overflow in Windows Kernel allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in the Windows Kernel lets a low-privileged, authenticated attacker gain SYSTEM-level control by triggering a heap-based buffer overflow (CWE-122). The flaw spans a broad platform range from Windows 10 1607 through Windows 11 26H1 and Windows Server 2012 through Server 2025, and was reported internally by Microsoft. No public exploit is identified at time of analysis and it is not in CISA KEV, but the ubiquity of the affected component plus full high impact on confidentiality, integrity, and availability make it a meaningful patch priority.
Technical ContextAI
The vulnerability resides in the Windows Kernel (ntoskrnl and associated kernel-mode components), the most privileged code layer of the OS, running in ring 0 with unrestricted access to memory and hardware. CWE-122 (Heap-Based Buffer Overflow) indicates a kernel pool/heap allocation is written past its bounds, typically due to inadequate length validation on attacker-influenced data crossing the user-to-kernel boundary via a syscall or IOCTL. Corrupting adjacent kernel pool structures can be leveraged to overwrite function pointers or object headers, converting a memory-safety defect into arbitrary kernel-mode code execution. The CPE data confirms the affected surface is the base OS across Windows 10 (1607, 1809, 21H2, 22H2), Windows 11 (24H2, 25H2, 26H1), and Windows Server 2012/2012 R2/2016/2019/2022/2025, including Server Core installations.
RemediationAI
Patch available per vendor advisory - apply the Microsoft security update for your specific Windows edition and build as published in the MSRC update guide at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50332; the exact fixed KB/build differs per release and should be taken from that advisory rather than assumed. Prioritize multi-user, RDP-accessible, and shared-workstation hosts where untrusted local users can run code, since those maximize the value of a local EoP. As kernel EoP flaws have no clean feature-level workaround, if immediate patching is impossible the practical compensating controls are to restrict local/interactive logon and code-execution rights to trusted accounts, enforce least privilege, and enable exploit mitigations (Hypervisor-protected Code Integrity/VBS and kernel pool hardening) to raise exploitation cost - with the trade-off that VBS/HVCI can affect performance and driver compatibility and does not guarantee prevention.
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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
Leaving vuln.today