CVE-2026-50341

What it actually does

This is a local information disclosure vulnerability in the Windows NTFS file system implementation caused by a buffer over-read. A locally authenticated attacker can trigger NTFS to read beyond the intended memory boundary and disclose data that should not be accessible to the attacker. The vulnerability affects confidentiality only: it does not directly allow code execution, privilege escalation, data modification, or denial of service based on the provided CVSS vector.

Why it matters to the business

Successful exploitation could expose sensitive information from affected Windows workstations or servers to a user or process that already has local access. In practice, the greatest risk is as a supporting step in a broader intrusion, where leaked memory or filesystem-related information may help an attacker understand the system, bypass protections, or prepare follow-on attacks. The issue is not currently listed in CISA KEV, is not reported as ransomware-used, has low EPSS likelihood, and has no stated exploit maturity, but it still warrants normal patching across supported Windows endpoints and servers because NTFS is a core operating system component.

How an attack unfolds

An attacker first needs valid local access to an affected Windows system, such as through an existing user account, malware running as a low-privileged process, or access gained through another vulnerability. The attacker then interacts with NTFS in a way that triggers the vulnerable buffer over-read condition. If successful, NTFS returns or exposes data outside the expected buffer boundary, allowing the attacker to obtain information that should not be available to that security context. The disclosed information may then be used to support reconnaissance, credential or token targeting, exploit reliability improvements, or other follow-on activity, but the vulnerability by itself does not provide remote access or arbitrary code execution.

How to fix it

Apply the Microsoft security update that addresses this NTFS information disclosure vulnerability for all affected Windows versions, including Windows 10, Windows 11, Windows Server 2012, Windows Server 2016, Windows Server 2019, Windows Server 2022, and Windows Server 2025. Because exact fixed build numbers or KB identifiers were not provided, use Microsoft Update, Windows Update for Business, WSUS, Microsoft Configuration Manager, or the Microsoft Security Update Guide to identify and deploy the applicable July 2026 or later cumulative/security update for each affected operating system release. Where immediate patching is not possible, reduce exposure by limiting local interactive access, removing unnecessary local users, enforcing least privilege, restricting untrusted code execution, and prioritizing systems where untrusted users can log on or run workloads.

How to confirm the fix worked

Confirm remediation by verifying that each affected Windows host has installed the Microsoft security update that supersedes or fixes this vulnerability for its exact OS version and build. Use centralized patch management reporting, Windows Update history, installed hotfix inventory, and OS build compliance checks to ensure systems are at or above the vendor-fixed patch level. Validate that unsupported or end-of-service Windows releases are either covered by an applicable extended security update program or removed from production. For exposure validation, inventory all affected Windows 10, Windows 11, and Windows Server versions listed in the advisory and compare them against current patch status.

Typical attack path

1. Obtain local access to an affected Windows workstation or server using valid credentials, malware execution, or another foothold.
2. Run a local process that interacts with NTFS using crafted filesystem operations intended to trigger the buffer over-read.
3. Cause NTFS to read beyond the intended memory boundary.
4. Collect any disclosed information returned to the local attacker-controlled process.
5. Use the leaked information to aid further local reconnaissance, security bypass attempts, or chaining with other vulnerabilities.

How to detect it

Post-exploitation detection is difficult because this vulnerability is a local information disclosure issue and may not produce a distinctive network event, authentication event, or crash. Focus on identifying suspicious local activity around the time of potential exploitation: unusual processes performing intensive or abnormal filesystem operations, unexpected access to raw volumes or NTFS metadata, suspicious execution from temporary/user-writable directories, endpoint detections involving custom exploit tools, and activity by low-privileged users on systems where they do not normally run code. Relevant telemetry sources include EDR process and file activity, Windows Security logs for local logon and process creation if enabled, Sysmon process creation and file access events, PowerShell logs, Defender for Endpoint advanced hunting data, application control logs, and crash or Windows Error Reporting events involving filesystem-related components. Because no public exploit indicators, threat actors, or stable artifacts were provided, prioritize behavioral investigation over static IOC matching.

What your security team should do

• Deploy the applicable Microsoft cumulative/security update to affected Windows endpoints and servers through standard patch management, prioritizing systems that allow local user logon, shared workstations, terminal servers, developer workstations, and multi-user servers.
• Inventory affected Windows versions and identify any unsupported, unmanaged, or patch-lagging systems.
• Apply least-privilege controls to reduce the number of users and processes that can execute code locally on sensitive systems.
• Review endpoint protection and application control coverage to reduce the risk of a low-privileged local process being used to trigger the vulnerability.
• Monitor Microsoft Security Update Guide, CISA KEV, and threat intelligence sources for any change in exploit maturity, public proof-of-concept availability, or active exploitation reporting.
• Because there are no currently reported KEV or ransomware associations and EPSS is low, handle as a normal-priority operating system patch unless local exposure is high or the asset is especially sensitive.