Severity by source
AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Local NTFS parsing flaw needing a user to open/mount crafted content (AV:L, UI:R), no attacker privileges (PR:N), with full kernel-context code execution giving high C/I/A.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
Lifecycle Timeline
2DescriptionCVE.org
Heap-based buffer overflow in Windows NTFS allows an unauthorized attacker to execute code locally.
AnalysisAI
Local code execution in the Windows NTFS driver (CVE-2026-49797) allows an attacker with local access to run arbitrary code by tricking a user into interacting with a maliciously crafted NTFS artifact, exploiting a heap-based buffer overflow (CWE-122). The flaw affects a broad range of Windows client and server releases from Windows 10 1607 and Server 2012 through Windows 11 26H1 and Server 2025. Microsoft has released a patch; no public exploit identified at time of analysis and it is not listed in CISA KEV.
Technical ContextAI
The vulnerability resides in NTFS (New Technology File System), the default file system driver in Windows, which runs in kernel mode and parses on-disk metadata structures such as the Master File Table, attributes, and index records. CWE-122 (heap-based buffer overflow) indicates that NTFS allocates a heap buffer and writes past its bounds while parsing attacker-influenced file system data - for example malformed metadata on a crafted volume, disk image, or file. Because NTFS parsing occurs in a privileged kernel context, a controlled heap overflow here can corrupt adjacent kernel objects and lead to arbitrary code execution. The CPE data enumerates Microsoft Windows 10 (1607, 1809, 21H2, 22H2), Windows 11 (24H2, 25H2, 26H1), and Windows Server 2012 through 2025 as affected products.
RemediationAI
Apply the Microsoft security update for CVE-2026-49797 via the MSRC advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-49797; a vendor patch is available, and administrators should deploy the corresponding monthly cumulative update / KB for each affected Windows 10, Windows 11, and Windows Server 2012-2025 build through Windows Update or WSUS/SCCM. Because exploitation requires user interaction with attacker-supplied NTFS content, compensating controls until patching completes include restricting the mounting of untrusted disk images, VHD/VHDX files, and removable/external NTFS volumes (via Group Policy device installation restrictions), which trades off legitimate removable-media workflows, and educating users not to open or mount untrusted images. Given the broad OS footprint, prioritize patching over workarounds, as no configuration change fully removes the NTFS parsing exposure.
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Same weakness CWE-122 – Heap-based Buffer Overflow
View allSame technique Heap Overflow
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External POC / Exploit Code
Leaving vuln.today
EUVD-2026-43812
GHSA-7fcf-6p48-fvvr