CVE-2025-50167 in Windows
Summary
by MITRE • 08/12/2025
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Hyper-V allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 11/22/2025
This vulnerability represents a critical race condition flaw within Windows Hyper-V's concurrent execution mechanisms that enables local privilege escalation for authorized attackers. The issue stems from improper synchronization controls when multiple execution threads access shared resources simultaneously, creating opportunities for malicious exploitation. The vulnerability exists in the Hyper-V hypervisor component where concurrent operations fail to properly coordinate access to shared memory segments or system resources, allowing an attacker to manipulate the timing and sequence of operations to gain elevated privileges. This race condition manifests when legitimate system processes and malicious code attempt to access the same shared resource concurrently without adequate mutual exclusion mechanisms. The flaw specifically affects the hypervisor's resource management protocols where multiple threads or processes can simultaneously attempt to modify or access critical system data structures, leading to unpredictable behavior that can be exploited for privilege escalation.
The technical implementation of this vulnerability involves the hypervisor's failure to properly implement atomic operations or mutex locks when managing shared resources between concurrent execution threads. Attackers can exploit this by carefully timing their malicious code execution to coincide with legitimate system operations that access the vulnerable shared resources. This creates a window of opportunity where the attacker can manipulate the state of the shared resource during the race condition, potentially allowing them to modify system parameters, access restricted memory regions, or alter privilege levels. The vulnerability requires local system access and authentication since the attacker must already have a valid user account to execute malicious code, but once exploited, it provides the ability to elevate privileges to system level. The improper synchronization occurs at the kernel level within Hyper-V's resource management subsystem, where the hypervisor fails to enforce proper locking mechanisms that would prevent concurrent access to critical data structures.
The operational impact of this vulnerability extends beyond simple privilege escalation to potentially compromise the entire virtualization environment. An attacker who successfully exploits this race condition can gain system-level privileges and subsequently compromise all virtual machines running on the affected Hyper-V host, as well as potentially access sensitive data stored within the virtualized environment. The vulnerability affects Windows systems running Hyper-V with specific versions of the Windows operating system, particularly those that have not received the relevant security patches. This creates a significant risk for enterprise environments where Hyper-V is extensively used for virtualization, as a single compromised local account could potentially provide attackers with complete control over the host system and all virtual machines running on it. The exploitation process typically involves creating multiple threads that race to access and modify shared resources, with the attacker's code attempting to manipulate the outcome of these concurrent operations to achieve privilege escalation.
Mitigation strategies for this vulnerability focus on both immediate patching and operational security improvements. Microsoft has released security updates that address the race condition by implementing proper synchronization controls and mutex locks within the Hyper-V hypervisor components. Organizations should prioritize applying these patches as soon as possible, particularly in environments where Hyper-V is actively used for virtualization. Additionally, implementing operational controls such as privilege separation, limiting local user accounts to minimum necessary permissions, and monitoring for suspicious concurrent execution patterns can help reduce the attack surface. The vulnerability aligns with CWE-362, which describes race conditions in concurrent systems, and maps to ATT&CK technique T1068, which covers local privilege escalation through race conditions. Security teams should also consider implementing behavioral monitoring to detect anomalous concurrent access patterns that might indicate exploitation attempts, and should review system configurations to ensure that Hyper-V is properly isolated from potentially compromised user environments. Network segmentation and least privilege principles should be enforced to minimize the potential impact if exploitation occurs, as the vulnerability requires local access but could provide complete system compromise once successful.