Windows NTFS CVE-2026-69340

The attacker must hold a valid low-privilege Windows account or network share credentials sufficient for SMB authentication (PR:L). A local or remote user on the target system must perform an action that causes the vulnerable NTFS code path to execute - such as opening or accessing a specially crafted file on the share (UI:R). High attack complexity (AC:H) means exploitation is not straightforward: specific memory layout or timing conditions must be satisfied, consistent with kernel heap exploitation techniques. The vulnerability is inherent to NTFS-formatted volumes accessible over the network, which is the default for Windows file servers with any shared folders configured. Environments where SMB network shares are not exposed to low-privilege or untrusted users, or where inbound SMB is blocked at the perimeter, materially reduce exploitation likelihood.

The CVSS 7.1 score and vector AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H characterize a network-reachable but non-trivial exploitation scenario. The high attack complexity and mandatory user interaction substantially reduce opportunistic automation, distinguishing this from the mass-exploitable class of network RCEs. PR:L confirms a valid low-privilege Windows account or network share credential is a prerequisite, ruling out fully unauthenticated exploitation. The C:H/I:H/A:H triad indicates that a successful exploit yields full kernel-level compromise - not merely information disclosure. The breadth of affected OS versions (nineteen distinct SKUs from Server 2012 to Windows 11 26H1) creates wide organizational exposure even if per-host exploitation probability is moderate. No EPSS data was provided, and KEV status is unconfirmed; the combination of AC:H and UI:R suggests exploitation is targeted rather than automated at scale. The absence of a public exploit at this time further reduces immediate mass-exploitation risk, though the high post-exploitation impact warrants prompt patching in file-server and domain environments.

An authenticated low-privilege domain user targets a Windows file server by connecting to an exposed NTFS network share and triggering a user-side action - such as opening a specially crafted file - that causes the NTFS kernel driver to process malformed filesystem metadata, overflowing a heap buffer in ntfs.sys. The controlled overflow allows the attacker to corrupt kernel structures and redirect execution, elevating from their low-privilege session to SYSTEM. No public exploit code is known at this time, and the AC:H rating indicates reliable exploitation requires careful heap grooming.