CVE-2026-50313

What it actually does

This vulnerability is a heap-based buffer overflow in the Windows NTFS file system handling code. A local, unauthenticated attacker can trigger memory corruption by causing a vulnerable Windows system to process specially crafted NTFS content, such as a malicious local volume, removable media, disk image, or file-system structure. Successful exploitation can result in arbitrary code execution in the local context of the affected component, potentially leading to full compromise of confidentiality, integrity, and availability on the targeted system. The CVSS vector indicates local attack requirements, low attack complexity, no privileges required, and user interaction required.

Why it matters to the business

If exploited, this flaw could allow an attacker to take control of an affected Windows workstation or server after a user or system interacts with malicious NTFS-formatted content. Business consequences may include malware execution, endpoint compromise, credential theft, data tampering, service disruption, and use of the compromised host as a foothold for lateral movement. The vulnerability affects many supported Windows client and server versions, increasing operational exposure across mixed Windows fleets. It is not currently listed in CISA KEV, has no reported ransomware association, and has low EPSS at this time, but the high technical impact means it should still be remediated through normal high-priority patching.

How an attack unfolds

An attacker prepares specially crafted NTFS content designed to corrupt heap memory when parsed by a vulnerable Windows system. The content may be delivered through a removable drive, mounted virtual disk, downloaded disk image, archive-expanded volume, or another workflow that causes Windows to inspect or mount the malicious NTFS structure. Because the vulnerability requires local access and user interaction, the attacker typically relies on social engineering, physical media, a staged payload, or prior access to place the crafted content where it will be processed. When the vulnerable NTFS code handles the malformed structure, the heap overflow can be triggered. If the attacker reliably controls memory layout and execution flow, they may execute code on the local machine, install malware, alter files, or pivot to additional systems.

How to fix it

Apply the Microsoft security update that remediates this NTFS vulnerability for all affected Windows versions, including Windows 10, Windows 11, and Windows Server 2012 through Windows Server 2025. Because exact fixed build numbers were not provided in the input, use Microsoft Security Update Guide, Windows Update, WSUS, Microsoft Configuration Manager, or equivalent patch management tooling to identify and deploy the applicable cumulative update for each operating system release. Prioritize endpoints and servers that commonly handle removable media, user-downloaded disk images, virtual hard disks, file ingestion workflows, or untrusted storage. Where immediate patching is not possible, reduce exposure by restricting mounting of untrusted removable media and virtual disks, disabling AutoPlay/AutoRun, blocking untrusted VHD/VHDX/ISO workflows where feasible, enforcing least privilege, and ensuring endpoint protection scans newly introduced storage media.

How to confirm the fix worked

Confirm affected systems have received the relevant Microsoft cumulative security update by checking Windows Update history, installed KBs, OS build numbers, or enterprise patch compliance reports against Microsoft’s official guidance for this vulnerability. Validate that all affected Windows 10, Windows 11, and Windows Server versions are either patched, isolated, or otherwise mitigated. Test representative systems by verifying the NTFS driver and OS build correspond to the patched release level. Review endpoint policy to confirm AutoPlay/AutoRun restrictions and removable media controls are enforced where used as compensating controls. Vulnerability scanners should be updated and run after patch deployment to confirm the CVE is no longer reported.

Typical attack path

1. Create or obtain malicious NTFS-formatted content designed to trigger the heap overflow.
2. Deliver the crafted content to a target system through removable media, a virtual disk image, a downloaded file, or another local interaction path.
3. Induce a user or system process to mount, open, scan, index, or otherwise process the crafted NTFS content.
4. Trigger memory corruption in the vulnerable NTFS handling code.
5. Gain local code execution if exploitation is successful.
6. Run follow-on actions such as payload deployment, credential access, persistence, data theft, or lateral movement.

How to detect it

There are no public exploit indicators provided and no known KEV or ransomware exploitation status for this vulnerability. Detection should focus on evidence that a system processed suspicious NTFS media or disk images followed by crashes, abnormal process behavior, or malware execution. Review Windows Event Logs including System, Security, Microsoft-Windows-Kernel-PnP, Microsoft-Windows-DriverFrameworks-UserMode, Microsoft-Windows-Partition, and storage-related operational logs for unexpected disk arrivals, volume mounts, driver errors, file-system corruption, bug checks, or NTFS events. Correlate those events with user activity, downloads, removable media insertion, mounting of VHD/VHDX/ISO files, and endpoint alerts. On endpoints, hunt for unusual use of mountvol.exe, diskpart.exe, PowerShell Mount-DiskImage, or third-party virtual disk tools, especially when followed by unexpected process creation, privilege escalation behavior, credential access, persistence creation, or outbound network connections. For forensic review, examine recent removable media artifacts, mounted device history, shellbags, LNK files, RecentDocs, downloaded disk images, prefetch entries, crash dumps, and EDR memory-corruption or exploit-prevention events involving NTFS or storage drivers.

• ntfs.sys
• mountvol.exe
• diskpart.exe
• Mount-DiskImage
• vhdmp.sys
• .vhd
• .vhdx
• .iso
• Microsoft-Windows-Kernel-PnP
• Microsoft-Windows-DriverFrameworks-UserMode
• Microsoft-Windows-Partition
• Microsoft-Windows-Ntfs
• Event ID 1001
• BugCheck
• NTFS file system structure is corrupt
• The file system structure on the disk is corrupt and unusable
• AutoPlay
• AutoRun

What your security team should do

• Deploy the applicable Microsoft security update across affected Windows client and server versions, prioritizing systems exposed to removable media, disk image handling, or untrusted file ingestion.
• Update vulnerability scanners and confirm all affected Windows 10, Windows 11, and Windows Server assets are assessed for this issue.
• Temporarily restrict or monitor mounting of untrusted VHD, VHDX, ISO, USB, and other removable or virtual storage media until patching is complete.
• Disable AutoPlay and AutoRun through Group Policy or equivalent device management controls where not already enforced.
• Review endpoint telemetry for unusual mounting of virtual disks or removable media followed by crashes, exploit-like behavior, suspicious child processes, or malware execution.
• Ensure EDR, antivirus, and attack surface reduction policies are active on systems where users can open downloaded files or mount external media.
• Because this is not currently in KEV and has low EPSS, handle as high-impact routine patching rather than emergency exploitation response unless local telemetry shows suspicious activity.