CVE-2026-20941 in Windows
Summary
by MITRE • 01/13/2026
Improper link resolution before file access ('link following') in Host Process for Windows Tasks allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 01/24/2026
This vulnerability exists in the host process for windows tasks and represents a critical privilege escalation flaw that affects authorized attackers with local access. The issue stems from improper link resolution before file access, creating a dangerous condition where symbolic links or hard links can be manipulated to redirect file operations to unintended locations. The vulnerability specifically targets the Windows task execution environment where the host process handles task scheduling and execution, making it particularly dangerous as it operates within the system's core task management infrastructure. This flaw allows an attacker who already possesses local user privileges to escalate their access level by exploiting the insecure handling of file references during task execution processes.
The technical implementation of this vulnerability involves the host process failing to properly validate or resolve symbolic links before performing file access operations. When a task is scheduled or executed, the process may follow symbolic links without adequate verification of the target path, potentially allowing an attacker to create malicious symbolic links that point to sensitive system files or directories. This insecure link resolution mechanism directly violates the principle of least privilege and creates a pathway for attackers to bypass normal access controls. The flaw operates at the operating system level within the Windows task scheduler architecture, specifically affecting how the host process resolves file paths during task execution cycles. According to the CWE database, this vulnerability maps to CWE-59, which describes improper link resolution before file access, a category that encompasses various path traversal and link following vulnerabilities that can lead to privilege escalation.
The operational impact of this vulnerability extends beyond simple privilege escalation as it provides attackers with persistent access to system resources that would normally be restricted. An attacker can leverage this flaw to gain administrative privileges or access to protected system components, potentially leading to complete system compromise. The vulnerability's exploitation requires local access, making it particularly concerning for environments where physical or remote access may be available to untrusted parties. Attackers can use this privilege escalation to modify system files, install malicious software, or establish persistent backdoors within the Windows task execution framework. This vulnerability directly maps to several ATT&CK techniques including privilege escalation through scheduled tasks and abuse of Windows system binaries, making it a significant concern for enterprise security postures.
Mitigation strategies for this vulnerability should focus on both immediate system hardening and long-term architectural improvements. System administrators should implement strict file permissions and access controls, particularly around task scheduling directories and system task execution paths. The Windows task scheduler should be configured to disable unnecessary task execution capabilities and implement additional validation of symbolic links before file access operations. Regular system updates and patches should be applied immediately upon availability, as this vulnerability likely affects multiple Windows versions and task execution environments. Organizations should also implement monitoring solutions that detect suspicious symbolic link creation or modification in critical system directories. Additional defensive measures include implementing application whitelisting policies, restricting local user access to task scheduling components, and conducting regular security audits of task execution environments. The vulnerability demonstrates the importance of proper input validation and path resolution in system-level processes, emphasizing that even authorized processes must maintain strict security boundaries when handling file operations.