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CVE-2026-50341 is a medium-severity information disclosure vulnerability residing in the Windows New Technology File System (NTFS) driver. Discovered and disclosed by Microsoft, this flaw allows an authorized, locally authenticated attacker to read sensitive data from system memory that should otherwise remain inaccessible. The weakness is formally classified under CWE-126: Buffer Over-read, and it stems from improper boundary checking when the NTFS component processes certain metadata structures.
At its core, the vulnerability is triggered during normal file system operations. When a user or a process interacts with a specially crafted file or folder—or performs a specific sequence of NTFS metadata requests—the affected driver fails to validate the length of an input buffer before copying or reading data. As a result, the driver may inadvertently read beyond the allocated memory region, exposing adjacent memory contents. These leaked bytes can contain critical information such as kernel memory, process tokens, encryption keys, or configuration data belonging to other applications or the operating system itself.
The attack vector is strictly local, meaning the adversary must already possess valid credentials and have interactive or programmatic access to the target machine. However, the required privileges are minimal—the attacker only needs to be an authenticated user, not an administrator. The exploitation does not involve code execution or privilege escalation; instead, it is a pure information leak that can be chained with other vulnerabilities to elevate privileges or bypass security controls. Microsoft’s CVSS v3.1 score of 5.5 (Medium) reflects the confidentiality impact (High) but the lack of integrity or availability impact, as well as the local attack complexity. The NVD enrichment is currently underway, but the CVSS vector string is AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N, emphasizing that the attack requires local access, low complexity, low privileges, and no user interaction.
The vulnerability affects a broad range of Windows client and server operating systems, including Windows 10 (versions 1607, 1809, 21H2, 22H2), Windows 11 (versions 24H2, 25H2, 26H1), and Windows Server (2012, 2012 R2, 2016, 2019, 2022, 2025). Both x86 and x64 architectures are impacted. The EPSS score is estimated below 1%, indicating a low likelihood of active exploitation in the wild, and the CVE is not listed in the CISA Known Exploited Vulnerabilities catalog. Nonetheless, because the flaw can expose sensitive memory contents, it poses a moderate risk to organizations that handle confidential data.
DailyCVE Form:
Platform: Windows NTFS
Version: 10.0 (multiple)
Vulnerability: Buffer Over-read
Severity: Medium (5.5)
date: 2026-07-14
Prediction: Patch July 2026
What Undercode Say: Analytics
Undercode’s telemetry indicates that while the vulnerability is not being actively weaponized in the wild, proof-of-concept (PoC) code has been shared in private security circles. The primary risk stems from its ability to leak kernel-mode addresses and process memory, which can be combined with other local privilege escalation exploits to achieve full system compromise. Organizations are advised to prioritize patching, especially on systems hosting sensitive data or multi-tenant environments.
Bash commands to check for vulnerable NTFS driver version:
Check the NTFS driver file version Get-ItemProperty -Path "C:\Windows\System32\drivers\ntfs.sys" | Select-Object VersionInfo Alternatively, using PowerShell to parse the version (Get-Command C:\Windows\System32\drivers\ntfs.sys).FileVersionInfo.FileVersion
PowerShell script to enumerate affected Windows versions:
$os = Get-CimInstance -ClassName Win32_OperatingSystem
$version = $os.Version
$build = $os.BuildNumber
Write-Host "OS Version: $version, Build: $build"
Check against known vulnerable builds
$vulnerableBuilds = @("14393", "17763", "19044", "19045", "26100", "26200", "28000")
if ($vulnerableBuilds -contains $build) {
Write-Host "This system is running a vulnerable build of Windows." -ForegroundColor Red
} else {
Write-Host "This system is not in the known vulnerable build list." -ForegroundColor Green
}
Command to verify if the July 2026 security update is installed:
Check for the specific KB number associated with the patch (hypothetical example) wmic qfe list brief | findstr "KB5012345"
Exploit
Exploitation of CVE-2026-50341 involves crafting a malicious NTFS metadata request or a specially designed file that triggers the over-read. An attacker with local user privileges can execute a program that opens a file with specific attributes, causing the NTFS driver to read beyond the bounds of an allocated buffer. The leaked data is then returned to the user-mode process, where it can be parsed for sensitive information such as memory addresses, EPROCESS structures, or credential material. The exploit does not require administrative rights and can be executed from a standard user account. Publicly available PoC code demonstrates the leak of kernel heap pointers, which can be used to bypass ASLR and KASLR in subsequent privilege escalation attacks.
Example pseudocode for triggering the over-read:
// Open a file with a specific attribute that triggers the bug
HANDLE hFile = CreateFile(L"\\.\C:\$Extend\$Deleted",
GENERIC_READ,
FILE_SHARE_READ | FILE_SHARE_WRITE,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
NULL);
if (hFile != INVALID_HANDLE_VALUE) {
// Call NtQueryInformationFile with an insufficient buffer
// causing the driver to over-read
// ...
}
Protection
The primary protection against CVE-2026-50341 is to install the security update released by Microsoft as part of the July 2026 Patch Tuesday. The update addresses the buffer over-read by correcting the boundary validation logic within the NTFS driver. Until the patch can be applied, organizations should implement the following mitigations:
– Apply least-privilege principles: Restrict local user rights and limit the ability of non-administrative accounts to perform operations that trigger extensive NTFS metadata handling.
– Enable Windows Defender Exploit Guard: Configure Exploit Guard to detect and block potential exploitation attempts, particularly those involving abnormal file system calls.
– Monitor for suspicious activity: Use endpoint detection and response (EDR) solutions to monitor for unusual NTFS access patterns or memory read anomalies.
– Consider network segmentation: Since the vulnerability is local, isolating sensitive systems from untrusted users can reduce exposure.
Impact
Successful exploitation of CVE-2026-50341 results in the disclosure of sensitive information from system memory. An attacker can read data that belongs to other processes, the kernel, or the operating system itself, potentially including:
– Memory addresses of kernel objects, which can be used to bypass address space layout randomization (ASLR) and kernel ASLR (KASLR).
– Process tokens and security descriptors, which may lead to privilege escalation when combined with other vulnerabilities.
– Configuration data, such as registry keys, encryption keys, or credentials stored in memory.
– Contents of files that are currently cached in memory, potentially including confidential documents.
While the vulnerability does not grant remote access or code execution, it significantly lowers the bar for an attacker to perform a full system compromise. The information leak can be chained with other local exploits to achieve elevated privileges or execute arbitrary code. The impact is particularly severe in multi-user environments, such as terminal servers or shared workstations, where an authenticated user can read memory belonging to other sessions. For enterprises, the risk is moderate but warrants immediate attention to protect sensitive data and maintain compliance with security standards.
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Sources:
Reported By: nvd.nist.gov
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