CVE-2026-50441 in Windows
Summary
by MITRE • 07/14/2026
Untrusted pointer dereference in Windows Resilient File System (ReFS) allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 07/14/2026
The vulnerability described represents a critical untrusted pointer dereference flaw within the Windows Resilient File System implementation that enables local privilege escalation for authenticated attackers. This issue resides in the core file system functionality that manages data integrity and storage reliability in ReFS environments, which is designed to provide fault tolerance and automatic data recovery capabilities. The flaw manifests when the system processes certain file operations or metadata updates where it fails to properly validate pointer references before dereferencing them, creating an exploitable condition that can be leveraged by malicious actors with local access.
The technical nature of this vulnerability aligns with CWE-476 which specifically addresses NULL pointer dereference conditions, though in this case the issue involves untrusted pointer dereference rather than simple null dereference. The flaw occurs during ReFS file system operations where kernel-mode components handle file metadata and storage structures without sufficient validation of input data or pointer integrity. When an authenticated user executes specific file operations within a ReFS volume, the system may process a pointer that has been manipulated or corrupted by malicious input, leading to unpredictable behavior including potential code execution in kernel space.
The operational impact of this vulnerability extends beyond simple privilege escalation as it represents a fundamental security weakness in Windows storage subsystems that could affect enterprise environments where ReFS is deployed for critical data storage. Organizations utilizing ReFS for fault-tolerant storage solutions face elevated risk when attackers gain local access to systems running these file systems, as the vulnerability can be exploited without requiring network connectivity or external attack vectors. The local privilege escalation capability means that even users with minimal system privileges could potentially elevate their access level to SYSTEM, providing complete control over affected systems and enabling further lateral movement within networks.
Mitigation strategies for this vulnerability should include immediate deployment of Microsoft security updates that address the specific pointer validation flaws in ReFS implementation, alongside comprehensive monitoring for suspicious file system activity or abnormal privilege escalation patterns. Security teams should implement additional controls such as mandatory access controls, restricted user accounts with minimal privileges, and regular audit of local file system operations to detect potential exploitation attempts. The ATT&CK framework categorizes this type of vulnerability under T1068 which covers 'Local Privilege Escalation' and specifically addresses techniques involving kernel vulnerabilities and memory corruption flaws that enable attackers to gain elevated system privileges through local access.
Organizations should also consider implementing network segmentation and principle of least privilege policies to limit the potential impact of successful exploitation, while maintaining robust endpoint detection and response capabilities to identify anomalous behavior patterns that may indicate attempted exploitation. Regular security assessments of file system components and kernel-mode drivers should be conducted to identify similar vulnerabilities in other storage subsystems, as this type of memory corruption flaw often indicates broader architectural weaknesses that could affect related components. The vulnerability demonstrates the critical importance of proper input validation and pointer integrity checking in kernel-mode code, particularly within storage and file system drivers where security implications can extend far beyond individual file operations to encompass complete system compromise.