CVE-2026-50389

What it actually does

This vulnerability is a local information disclosure flaw in Windows File Explorer. A low-privileged, authenticated attacker with local access can cause File Explorer to expose sensitive information that should not be accessible to that user. The CVSS vector indicates local attack requirements, low complexity, low privileges, no user interaction, unchanged scope, and high confidentiality impact, with no direct integrity or availability impact. It does not provide remote code execution or privilege escalation by itself, but disclosed data could support follow-on attacks such as credential discovery, lateral movement, or targeting of sensitive files.

Why it matters to the business

Successful exploitation could allow a local user or malware already running on a Windows workstation or server to access sensitive information, potentially exposing confidential files, operational data, user activity, or security-relevant details. The immediate business risk is data leakage rather than service outage. Because the issue affects many supported Windows desktop and server versions, organizations with broad Windows fleets should treat patching as part of routine endpoint and server hardening. The vulnerability is not currently listed in CISA KEV, is not known to be used in ransomware campaigns, has no reported exploit maturity, and has a low EPSS score, which suggests lower near-term exploitation likelihood compared with actively exploited Windows vulnerabilities.

How an attack unfolds

An attacker first needs local access to an affected Windows system as an authorized, low-privileged user or through malware already executing in that user context. The attacker then interacts with Windows File Explorer or triggers the vulnerable File Explorer behavior to retrieve information that should be protected from that account. The exposed information may be inspected directly, copied, or used to identify additional targets, credentials, file locations, or system details. Because exploitation is local and requires prior access, this flaw is most useful as a post-compromise discovery or data-access primitive rather than an initial intrusion vector.

How to fix it

Apply the Microsoft security update that addresses this vulnerability for all affected Windows versions, including Windows 10, Windows 11, Windows Server 2016, Windows Server 2019, Windows Server 2022, and Windows Server 2025. Where exact fixed build numbers are not available, deploy the latest cumulative update for the applicable supported Windows release from Microsoft Update, Windows Server Update Services, Microsoft Configuration Manager, or the Microsoft Update Catalog. Prioritize systems used by multiple users, jump hosts, administrator workstations, file servers, Remote Desktop Session Hosts, and endpoints handling sensitive data. If immediate patching is not possible, reduce risk by limiting interactive local access, restricting Remote Desktop access, enforcing least privilege, monitoring for unusual local discovery or file access behavior, and preventing untrusted code execution through application control and endpoint protection.

How to confirm the fix worked

Confirm that affected Windows systems have installed the Microsoft cumulative update that includes the fix. Validate through centralized patch management, Windows Update history, installed hotfix inventory, or endpoint management reporting. On individual systems, administrators can review installed updates using supported Windows management tooling such as Settings, Control Panel update history, PowerShell update inventory, or enterprise vulnerability scanners. Confirm that unsupported Windows releases are either upgraded to supported versions or isolated with compensating controls. Because this is an information disclosure issue with no public exploit indicators provided, validation should focus on patch presence, OS build compliance, and reduction of unnecessary local or interactive access.

Typical attack path

1. Obtain local access to an affected Windows workstation or server as a standard user, or execute malware in a standard user context.
2. Invoke or automate the vulnerable Windows File Explorer behavior that exposes sensitive information.
3. Review the disclosed information for confidential data, credential material, paths, filenames, user activity, or system details.
4. Copy or stage the exposed information for exfiltration or use it to plan follow-on activity.
5. Optionally combine the disclosed information with other weaknesses to escalate access, move laterally, or access additional data.

How to detect it

There are no known public exploit indicators, no CISA KEV listing, no known ransomware use, and no named threat actors associated with this vulnerability based on the provided information. Detection should therefore focus on post-compromise behaviors rather than a unique exploit signature. Review endpoint telemetry, Windows Security logs, Sysmon or EDR events, and file access auditing for suspicious local enumeration, unusual access to sensitive directories, unexpected copying or staging of files, and anomalous File Explorer activity by non-administrative users. Useful log sources include Windows Security event logs for logon activity and object access where enabled, PowerShell logs if scripts are used to automate discovery, EDR process and file telemetry, and data loss prevention or file auditing systems. Pay special attention to systems with interactive multi-user access, Remote Desktop use, administrator workstations, and servers storing sensitive files. Since exploitation is local, correlate suspicious File Explorer or file-access behavior with recent local logons, RDP sessions, newly created processes, removable media use, archive creation, or outbound transfers.

What your security team should do

• Inventory affected Windows desktop and server versions across the environment and identify systems missing the relevant cumulative security update.
• Patch broadly through normal Windows update channels, prioritizing shared systems, administrator endpoints, remote-access hosts, and systems containing sensitive information.
• Monitor vendor advisories for any change in exploit maturity, public proof-of-concept availability, KEV listing, or ransomware association.
• Use endpoint detection and response telemetry to look for unusual local discovery, suspicious File Explorer child processes, unexpected access to sensitive directories, and data staging behavior.
• Limit local logon and Remote Desktop permissions to authorized users only, especially on servers and administrative workstations.
• Enforce least privilege and application control to reduce the chance that malware can use this flaw after gaining local execution.
• Ensure sensitive data is protected with appropriate access controls so that a local information disclosure flaw has limited downstream impact.