CVE-2026-49184: Windows 10 1607 Buffer Overflow Flaw

CVE-2026-49184 Overview

CVE-2026-49184 is a heap-based buffer overflow [CWE-122] in the Windows New Technology File System (NTFS) driver. The flaw allows a local, low-privileged attacker to execute arbitrary code on affected systems. Microsoft published the advisory on 2026-07-14, and the vulnerability affects the full range of supported Windows client and server platforms, including Windows 10, Windows 11, and Windows Server 2012 through 2025.

Successful exploitation results in full compromise of confidentiality, integrity, and availability on the target host. Attackers can leverage this flaw to escalate privileges after initial access, making it a valuable secondary stage in intrusion chains.

Critical Impact
Local attackers can trigger a heap corruption inside the NTFS driver to execute code in the kernel context, leading to full system compromise across nearly all supported Windows versions.

Affected Products

Microsoft Windows 10 (1607, 1809, 21H2, 22H2) on x86, x64, and ARM64
Microsoft Windows 11 (24H2, 25H2, 26H1) on x64 and ARM64
Microsoft Windows Server 2012, 2012 R2, 2016, 2019, 2022, and 2025

Discovery Timeline

2026-07-14 - CVE-2026-49184 published to NVD
2026-07-20 - Last updated in NVD database

Technical Details for CVE-2026-49184

Vulnerability Analysis

The vulnerability resides in the NTFS driver (ntfs.sys), which manages on-disk metadata structures such as Master File Table (MFT) records, attribute lists, and index entries. A heap-based buffer overflow occurs when the driver processes a malformed NTFS structure and writes past the bounds of an allocated pool buffer. Because NTFS parsing runs in kernel mode, memory corruption in this component can be leveraged to execute code with SYSTEM-level privileges.

Exploitation requires local access and low privileges, but no user interaction. An attacker with the ability to attach or mount a crafted volume, such as a virtual hard disk (VHD) or removable media, can trigger the vulnerable parsing path. This is a common technique for turning otherwise passive file system flaws into reliable local privilege escalation primitives.

Root Cause

The root cause is insufficient bounds validation when NTFS parses attributes or index structures from a file system image. A length or offset field controlled by the on-disk metadata is trusted without verification against the size of the destination pool allocation, resulting in a heap corruption condition classified under [CWE-122].

Attack Vector

The attack vector is local. An attacker delivers a specially crafted NTFS image and induces the operating system to mount or parse it. Automatic mounting of removable media, VHD attachment through standard user tooling, or file system operations against a crafted image can all reach the vulnerable code path. Refer to the Microsoft Security Update Guide for authoritative technical details.

No verified public proof-of-concept exploit is available at the time of writing, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog.

Detection Methods for CVE-2026-49184

Indicators of Compromise

Unexpected mounting of VHD, VHDX, or ISO images from user-writable directories such as %TEMP% or user profile folders
Kernel bugcheck events (BSOD) referencing ntfs.sys on machines shortly after file system attach operations
Creation of new SYSTEM-level processes from parents running under standard user context
Windows Event Log entries showing pool corruption or driver faults associated with NTFS parsing

Detection Strategies

Hunt for PowerShell or diskpart invocations that call Mount-DiskImage, Mount-VHD, or attach vdisk from non-administrative user sessions
Correlate file system driver crashes with subsequent privilege elevation or new service creation events
Monitor for suspicious binaries dropping .vhd, .vhdx, or .iso files followed by mount operations within a short time window

Monitoring Recommendations

Enable kernel-mode crash dump collection and forward ntfs.sys fault events to a centralized SIEM for triage
Track EDR telemetry for parent-child process anomalies where standard users spawn SYSTEM-level processes
Audit removable media and virtual disk attach events on servers where such operations are not part of normal workflows

How to Mitigate CVE-2026-49184

Immediate Actions Required

Apply the Microsoft security update referenced in the Microsoft Security Update Guide to all affected Windows client and server systems
Prioritize patching multi-user systems, terminal servers, and virtual desktop infrastructure where local access is broadly available
Inventory endpoints running end-of-support Windows versions and plan remediation or isolation where patches are unavailable

Patch Information

Microsoft has released patches through the standard Windows Update channel. The consolidated advisory is available at the Microsoft Security Update Guide. Administrators should validate deployment through Windows Update for Business, WSUS, or Intune reporting to confirm coverage across all affected SKUs listed in the advisory.

Workarounds

Restrict standard users from mounting virtual disk images by removing the SeManageVolumePrivilege and related rights where operationally feasible
Disable AutoPlay and automatic mounting of removable media via Group Policy to reduce exposure to crafted NTFS volumes
Apply application control policies to block execution of diskpart.exe, Mount-DiskImage, and similar tools for non-administrative users
Segment and monitor jump hosts and shared workstations where local privilege escalation would materially expand attacker access

bash

# Group Policy: disable AutoPlay for all drives on affected hosts
# Computer Configuration > Administrative Templates > Windows Components > AutoPlay Policies
# Setting: "Turn off AutoPlay" = Enabled, Option = "All drives"

# Registry equivalent
reg add "HKLM\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer" /v NoDriveTypeAutoRun /t REG_DWORD /d 0xFF /f