CVE-2025-53788 in Windows Subsystem for Linux
Summary
by MITRE • 08/12/2025
Time-of-check time-of-use (toctou) race condition in Windows Subsystem for Linux allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 08/19/2025
The vulnerability identified as CVE-2025-53788 represents a critical time-of-check time-of-use race condition within the Windows Subsystem for Linux implementation, specifically affecting the local privilege escalation capabilities of authorized attackers. This flaw exists in the way the subsystem handles file access operations and permission checks, creating a window where an attacker can manipulate system resources between the moment a permission check is performed and when the actual resource operation occurs. The vulnerability is particularly concerning because it operates within the trusted environment of a legitimate user session, making detection more challenging and exploitation more feasible.
The technical implementation of this race condition stems from improper synchronization mechanisms in the WSL kernel components responsible for managing file system access controls. When a user process requests access to a file or directory within the WSL environment, the system performs a permission check at a specific point in time before executing the actual file operation. However, the window between this check and the execution allows an attacker to modify the target resource, potentially changing permissions, replacing files, or altering the file system state in ways that would otherwise be prevented. This timing discrepancy creates a scenario where an attacker can bypass security controls through careful manipulation of the system state during this critical interval.
From an operational impact perspective, this vulnerability enables a local attacker with a valid user account to escalate privileges from standard user level to administrator or root access within the WSL environment. The attack vector requires the attacker to already possess legitimate user credentials, which makes the vulnerability less severe than remote exploits but still highly dangerous in environments where user accounts may be compromised or where insider threats exist. The privilege escalation occurs through the manipulation of file system objects that are subject to access control mechanisms, allowing the attacker to gain elevated privileges by exploiting the race condition in the permission checking process. This capability directly violates the principle of least privilege and can lead to complete system compromise when combined with other exploitation techniques.
The vulnerability aligns with CWE-367, which specifically addresses Time-of-Check to Time-of-Use race conditions, and demonstrates characteristics consistent with ATT&CK technique T1068, which covers local privilege escalation through race conditions. Security professionals should note that this issue affects Windows versions supporting WSL2, particularly those where the subsystem has been configured with elevated privileges or where user accounts have been granted additional access rights. The exploitation process typically involves creating a race condition scenario where an attacker can replace or modify files that are accessed by privileged processes within the WSL environment, thereby gaining unauthorized access to system resources. Mitigation strategies include applying Microsoft security updates as soon as they become available, implementing additional access control measures for sensitive WSL resources, and monitoring for unusual file system access patterns that may indicate exploitation attempts.
Organizations should prioritize patch management for this vulnerability, as Microsoft has released security updates addressing the race condition in WSL components. System administrators should also consider implementing additional monitoring controls to detect potential exploitation attempts, particularly focusing on file system operations that occur during privilege escalation scenarios. The vulnerability highlights the importance of proper synchronization mechanisms in kernel-level components and serves as a reminder that even trusted subsystems can contain security flaws that allow for privilege escalation when race conditions are not properly handled. Regular security assessments of WSL configurations and access controls are recommended to identify and remediate similar vulnerabilities before they can be exploited by malicious actors.