CVE-2026-62728 in Windows
Summary
by MITRE • 08/11/2026
Time-of-check time-of-use (toctou) race condition in Windows Common Log File System Driver allows an authorized attacker to elevate privileges locally.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 08/11/2026
A time-of-check time-of-use race condition vulnerability exists within the Windows Common Log File System Driver, specifically affecting the clogfs.sys component that handles common log file system operations. This flaw occurs when the system performs a permission check at one moment and subsequently accesses the same resource at a later moment without revalidating the access permissions, creating an exploitable window where malicious actors can manipulate the system state between these two points.
The vulnerability stems from improper synchronization mechanisms within the kernel-mode driver that processes log file operations through the Common Log File System. When an authenticated user attempts to perform operations on log files, the system initially verifies access permissions and then proceeds with the actual file manipulation. During this interval, an attacker can exploit the race condition by modifying the target resource or replacing it with a malicious alternative, effectively bypassing the initial permission validation.
This privilege escalation vulnerability operates under the context of the Common Weakness Enumeration CWE-367, specifically categorized as a Time-of-Check to Time-of-Use race condition. The attack vector requires local system access and leverages the principle that file operations in Windows are not atomic across the permission check and actual resource manipulation phases. Attackers can exploit this by creating symbolic links or hard links to target files during the vulnerable window, allowing them to gain elevated privileges through the exploitation of the race condition.
The operational impact of this vulnerability allows an authorized attacker with standard user privileges to escalate their access level to system-level privileges, effectively bypassing Windows security controls. The attack is particularly concerning because it operates within the kernel space where the driver runs, making detection and prevention more challenging. Successful exploitation can lead to complete system compromise, data exfiltration, and persistent access to network resources. This vulnerability aligns with several MITRE ATT&CK techniques including privilege escalation through kernel exploits and persistence mechanisms that leverage system drivers.
Mitigation strategies include applying Microsoft security updates that address the race condition in the clogfs.sys driver, implementing proper access controls for log file operations, and configuring system policies to prevent unauthorized modification of critical system components. Organizations should also monitor for suspicious file creation patterns and implement automated patch management systems to ensure timely remediation of such kernel-level vulnerabilities. The vulnerability demonstrates the importance of proper synchronization mechanisms in kernel drivers and highlights the need for comprehensive security testing of system components that handle privileged operations.