EUVD-2026-43804
GHSA-pw7v-3rcp-9vjc
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Local authenticated low-privileged attacker (AV:L/PR:L) triggers an in-kernel NTFS overflow with no user interaction, yielding SYSTEM-level total compromise (C/I/A:H).
Primary rating from Vendor (microsoft).
CVSS VectorNVD
Lifecycle Timeline
5DescriptionNVD
Stack-based buffer overflow in Windows NTFS allows an authorized attacker to elevate privileges locally.
AnalysisAI
Local privilege escalation in the Microsoft Windows NTFS driver lets an already-authenticated attacker overflow a stack buffer (CWE-121) to run code with full system-level privileges. It affects a broad swath of supported Windows client and server builds, from Windows 10 1607 and Server 2012 through Windows 11 26H1 and Server 2025. No public exploit identified at time of analysis, and CISA's SSVC framework currently rates exploitation as none; EPSS is low at 0.34% (26th percentile), so this is a patch-on-schedule elevation-of-privilege bug rather than an emergency.
Technical ContextAI
NTFS is the default on-disk filesystem for Windows, implemented largely in the kernel-mode driver ntfs.sys, which parses filesystem metadata (MFT records, attributes, reparse points, mount points) from disk or mounted volumes. CWE-121, a stack-based buffer overflow, indicates that a fixed-size stack buffer in this parsing/handling path is written past its bounds using attacker-influenced length or content. Because the code runs in kernel context, corrupting the kernel stack can overwrite return addresses or adjacent locals to hijack control flow. The CPE and EUVD data confirm the affected component is the Microsoft Windows operating system itself across many editions (windows_10_version_1607/1809/21H2/22H2, windows_11_version_24H2/25H2/26H1, and Windows Server 2012 through 2025, including Server Core installations), consistent with a shared kernel filesystem defect rather than an application-layer bug.
RemediationAI
Vendor-released patch: apply the Microsoft security update that raises each affected OS to at least its fixed build listed above (e.g., Windows 11 24H2/Server 2025 to 10.0.26100.8875/33158, Server 2022 to 10.0.20348.5386, Server 2012 R2 to 6.3.9600.23291) via Windows Update, WSUS, or your patch-management tooling; details are in the MSRC advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-49789. No filesystem-level workaround is published for an in-kernel NTFS parsing flaw, so patching is the only reliable fix. Until updates are deployed, reduce exposure by limiting who can run code or mount arbitrary volumes on affected hosts - restrict local/interactive logon rights, tighten application allow-listing to prevent attacker-supplied binaries from executing (the required foothold for this local EoP), and monitor for unexpected privilege escalations; note these controls only shrink the population of attackers who can reach the vulnerable code and do not remediate the defect.
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Same weakness CWE-121 – Stack-based Buffer Overflow
View allSame technique Buffer Overflow
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External POC / Exploit Code
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