CVE-2025-49751 in Windows
Summary
by MITRE • 08/12/2025
Missing synchronization in Windows Hyper-V allows an authorized attacker to deny service over an adjacent network.
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Analysis
by VulDB Data Team • 11/21/2025
The vulnerability identified as CVE-2025-49751 represents a critical weakness in Windows Hyper-V virtualization platform that stems from inadequate synchronization mechanisms within the hypervisor architecture. This flaw specifically affects systems running Hyper-V and creates a pathway for authorized but malicious actors to execute denial of service attacks against adjacent network hosts. The vulnerability manifests when the hypervisor fails to properly coordinate access to shared resources or communication channels between virtual machines and host systems, creating opportunities for exploitation that can disrupt normal operational functions. The security implications extend beyond simple service interruption as this weakness can potentially compromise the stability of entire virtualized environments where multiple VMs rely on synchronized resource access patterns.
The technical root cause of this vulnerability lies in the absence of proper mutual exclusion protocols and resource locking mechanisms within Hyper-V's network processing components. When authorized users or processes attempt to interact with Hyper-V managed network interfaces or virtual switches, the system fails to maintain consistent state management across concurrent operations. This synchronization failure creates race conditions where multiple processes can interfere with each other's network operations, leading to unpredictable behavior and potential service disruption. The flaw particularly impacts scenarios involving high-frequency network interactions or when multiple virtual machines are simultaneously accessing shared network resources through the same Hyper-V host infrastructure. According to CWE classification, this vulnerability maps to CWE-362, which specifically addresses race conditions that occur due to inadequate synchronization mechanisms in concurrent programming environments.
The operational impact of CVE-2025-49751 extends beyond simple network disruption to potentially compromise the integrity of virtualized computing environments that organizations rely upon for critical business operations. An attacker exploiting this vulnerability can systematically degrade network performance, cause virtual machine restarts, or create complete network outages within the affected Hyper-V environment. The adjacent network constraint means that exploitation requires physical or logical proximity to the target system, but this limitation does not mitigate the severity of potential damage. Organizations using Hyper-V for cloud computing services, development environments, or enterprise virtualization may experience cascading failures where a single compromised network interface can affect multiple virtual machines or entire virtualized networks. The vulnerability's impact is particularly concerning in environments where Hyper-V serves as a foundation for mission-critical applications or where network availability is paramount for business continuity.
Mitigation strategies for this vulnerability should focus on implementing comprehensive network segmentation and access control measures to limit the attack surface available to authorized users. Organizations should immediately apply Microsoft security updates and patches that address the synchronization issues within Hyper-V components, while also implementing network monitoring solutions that can detect unusual patterns of network activity that may indicate exploitation attempts. The implementation of proper network isolation techniques, including the use of virtual local area networks and network access control lists, can significantly reduce the potential impact of this vulnerability. Additionally, organizations should conduct thorough security assessments of their Hyper-V environments to identify and remediate any additional synchronization issues that may exist within their virtualized infrastructure. According to ATT&CK framework, this vulnerability aligns with techniques involving privilege escalation and denial of service, making it particularly dangerous when combined with other exploitation methods that could allow attackers to escalate their privileges within the virtualized environment.