CVE-2026-109453 in Windows
Summary
by MITRE • 10/14/2026
Heap-based buffer overflow in Virtual Hard Disk (VHD) Miniport Driver allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability described involves a heap-based buffer overflow within the Virtual Hard Disk VHD Miniport Driver, a critical component of the Windows operating system responsible for managing virtual hard disk operations. This driver facilitates communication between the hypervisor and guest operating systems by handling I/O requests related to virtual disks stored in formats such as VHD or VHDX. The presence of this specific flaw indicates that under certain conditions, the driver fails to properly validate input data before writing it to a pre-allocated buffer on the heap. This lack of boundary checking allows an attacker who has already gained local access with authorized credentials to write more data than the buffer can hold, thereby overwriting adjacent memory structures. Such memory corruption is particularly dangerous because the VHD Miniport Driver typically operates at high integrity levels within the kernel space, meaning that successful exploitation grants the attacker significant control over system resources and execution flow.
From a technical perspective, heap-based buffer overflows are among the most prevalent classes of software vulnerabilities due to their potential for arbitrary code execution or privilege escalation. In this context, an authorized local user can craft specific I/O requests containing malformed data designed to trigger the overflow condition. By carefully controlling the size and content of these requests, the attacker can overwrite critical heap metadata or function pointers located in memory adjacent to the vulnerable buffer. This manipulation allows for precise control over program execution flow during subsequent operations performed by the driver. The exploitation chain likely involves achieving arbitrary write primitives that facilitate code injection into kernel space, ultimately leading to a complete compromise of system integrity and confidentiality.
The operational impact of this vulnerability is severe due to its local nature combined with high privilege levels. Although it requires an authorized attacker to initiate the exploit, many enterprise environments rely on shared accounts or services running under elevated privileges where such access might be more easily obtained through social engineering or lateral movement from a compromised lower-privilege account. Once exploited, the vulnerability enables local privilege escalation, allowing the attacker to bypass standard security controls and gain SYSTEM-level access. This level of access permits the installation of rootkits, modification of system configurations, theft of sensitive data stored on virtual disks, and further pivoting within the network infrastructure. The ability to escalate privileges locally significantly lowers the barrier for attackers aiming to achieve full domain or host compromise in environments where VHD technology is actively used for virtualization workloads.
Mitigation strategies must address both immediate remediation and long-term architectural improvements. Microsoft has historically addressed such issues through security updates that patch the underlying code defects within the driver binaries, making it imperative for system administrators to apply all relevant cumulative updates promptly. Beyond patching, organizations should enforce strict least-privilege principles by minimizing the number of users or services granted local administrative rights on systems hosting virtual machines. Additionally, enabling advanced protection features such as Kernel Mode Hardware-enforced Stack Protection and Control Flow Guard can mitigate exploitation attempts even if a vulnerability exists in the driver code. Regular auditing of user permissions and monitoring for anomalous I/O patterns related to disk operations can also aid in early detection of potential exploitation activities before full system compromise occurs.
This vulnerability aligns with Common Weakness Enumeration identifier CWE-120, which classifies buffer copy without checking size limits as a fundamental memory safety error. Furthermore, the exploitation technique corresponds to MITRE ATT&CK tactic T1068, specifically subtechnique 1068.003 for Exploitation for Privilege Escalation via local kernel exploits. Understanding these mappings helps security teams contextualize the risk within broader threat landscapes and prioritize defensive measures accordingly. The reliance on heap memory management in high-integrity drivers underscores the importance of rigorous code review processes and static analysis tools during software development to prevent similar defects from entering production environments.