CVE-2020-16940 in Windows
Summary
by MITRE • 10/17/2020
<p>An elevation of privilege vulnerability exists when the Windows User Profile Service (ProfSvc) improperly handles junction points. An attacker who successfully exploited this vulnerability could delete files and folders in an elevated context.</p> <p>To exploit this vulnerability, an attacker would first have to log on to the system. An attacker could then run a specially crafted application that could exploit the vulnerability and delete files or folders of their choosing.</p> <p>The security update addresses the vulnerability by correcting how the Windows User Profile Service handles junction points.</p>
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Analysis
by VulDB Data Team • 02/25/2026
The vulnerability described in CVE-2020-16940 represents a critical elevation of privilege flaw within the Windows User Profile Service component known as ProfSvc. This issue stems from improper handling of junction points, which are symbolic links that redirect file system operations to different locations. The Windows User Profile Service is responsible for managing user profiles and their associated settings, making it a critical system component that requires careful security considerations. When junction points are improperly managed, they can create pathways for unauthorized access and manipulation of system resources that should remain protected.
The technical exploitation of this vulnerability requires an attacker to first establish a valid user session on the target system, which is a relatively common prerequisite for many Windows-based attacks. Once authenticated, the attacker can execute a malicious application specifically designed to trigger the junction point handling flaw within ProfSvc. This particular vulnerability enables the attacker to perform file system operations with elevated privileges, allowing them to delete files and folders that would normally be protected from modification by standard user accounts. The mechanism relies on the service's failure to properly validate or sanitize junction point references during profile processing operations.
From an operational impact perspective, this vulnerability presents a significant risk to system integrity and data protection. The ability to delete files and folders in an elevated context means that an attacker could potentially remove critical system files, user data, or security-related components that maintain system functionality and protection. This could lead to system instability, data loss, or even complete system compromise depending on which files are targeted. The vulnerability essentially allows for privilege escalation from a standard user account to a level that can manipulate core system resources, creating a substantial attack surface for malicious actors.
The security update for CVE-2020-16940 addresses this issue by implementing proper validation and handling of junction points within the Windows User Profile Service. This fix ensures that the service correctly processes symbolic links and does not inadvertently grant elevated privileges during file system operations. The remediation aligns with security best practices for handling symbolic links and junction points in operating system services, which is consistent with recommendations found in the CWE database under entries related to improper handling of symbolic links and privilege escalation vulnerabilities. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques and could potentially be leveraged as part of broader attack chains that exploit service misconfigurations to gain higher-level system access. Organizations should prioritize applying this patch to prevent exploitation and maintain system integrity against this specific elevation of privilege threat.