CVE-2026-105733 in Windows
Summary
by MITRE • 10/14/2026
Improper access control in Windows Hyper-V allows an authorized attacker to execute code locally.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability identified as improper access control within the Microsoft Windows Hyper-V component represents a critical security flaw that undermines the fundamental isolation guarantees provided by virtualization technologies. In standard operating procedures, Hyper-V is designed to enforce strict boundaries between the host operating system and its guest virtual machines, ensuring that processes running inside a VM cannot interfere with or access resources outside their designated environment without explicit permission. However, this specific weakness allows an authenticated attacker who has already gained local execution capabilities within a guest OS to bypass these isolation mechanisms. By exploiting the misconfigured permissions or logic errors in how Hyper-V handles requests from virtual machines, the attacker can escalate privileges and execute arbitrary code on the host system itself. This effectively breaks the security perimeter that is essential for multi-tenant environments and secure cloud infrastructure, transforming what should be an isolated guest environment into a potential vector for full host compromise.
From a technical perspective, this flaw typically stems from insufficient validation of access control lists or improper handling of inter-process communication channels between the virtual machine monitor and the underlying operating system kernel. When Hyper-V processes requests originating from a VM, it must verify that the requesting entity has the necessary privileges to perform the action. In this case, the verification process is flawed, allowing an attacker with low-level access within the guest OS to craft specific payloads or API calls that trick the hypervisor into executing code with host-level permissions. This type of vulnerability often involves manipulating memory structures or exploiting race conditions in how resources are allocated and managed across the virtualization boundary. The absence of rigorous checks on the source and intent of these requests enables the attacker to inject malicious instructions directly into the context of privileged system processes running on the host machine, leading to a complete loss of confidentiality, integrity, and availability for the physical server hosting the hypervisor.
The operational impact of this vulnerability is severe, particularly in enterprise environments where Hyper-V is used to host multiple critical workloads or sensitive data sets. An attacker who successfully exploits this flaw gains full control over the underlying hardware and operating system, which can lead to the exfiltration of confidential information from all virtual machines hosted on that server. Furthermore, the compromised host can be used as a pivot point for lateral movement within the network, allowing the attacker to target other systems that may not have direct internet exposure but are connected via internal networks. This scenario is particularly dangerous in cloud service provider environments or corporate data centers where resource sharing is common, as it compromises the trust model upon which virtualization relies. The ability to execute code locally with elevated privileges means that traditional endpoint protection solutions running within guest VMs may be rendered ineffective once the attacker gains access to the host layer, potentially allowing for persistent backdoors and advanced persistent threats that are difficult to detect using standard monitoring tools.
To mitigate this risk, organizations must prioritize applying the latest security patches released by Microsoft for their Windows Server environments hosting Hyper-V roles. Regular patch management is crucial as vendors frequently release updates addressing such access control flaws before they can be widely exploited in the wild. Additionally, administrators should implement strict least-privilege principles when configuring virtual machines and managing host resources, ensuring that guest accounts have only the minimum permissions necessary for their operations. Network segmentation strategies should also be employed to limit communication between VMs and the host management interfaces, reducing the attack surface available to potential intruders. For high-security environments, consider implementing additional layers of defense such as hardware-enforced stack protection features if supported by the CPU architecture, and continuously monitor system logs for anomalous behavior indicative of privilege escalation attempts or unauthorized access patterns related to virtualization components. Aligning these practices with industry standards like CWE-269 which covers Improper Privilege Management, helps in systematically identifying and remediating such weaknesses before they can be leveraged by malicious actors.