CVE-2026-62734 in Windows
Summary
by MITRE • 08/11/2026
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Telephony Service allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 08/11/2026
A race condition vulnerability exists in the Windows Telephony Service that enables local privilege escalation through improper synchronization of shared resources during concurrent execution. This flaw resides in the telephony service implementation where multiple threads or processes access common resources without adequate locking mechanisms, creating opportunities for malicious code exploitation.
The vulnerability stems from inadequate thread synchronization controls within the Windows Telephony Service component, which is designed to manage telephone communications and related services on Windows systems. When multiple operations attempt to modify shared data structures simultaneously, the lack of proper mutual exclusion mechanisms allows for unpredictable execution sequences that can be manipulated by an attacker. This race condition manifests when the service handles concurrent telephony operations such as call management, device enumeration, or configuration updates where shared memory regions are accessed without appropriate semaphore or mutex protection.
From a technical perspective, this vulnerability operates under the common weakness enumeration CWE-362 which specifically addresses race conditions in concurrent programming. The flaw allows an authenticated local attacker to exploit the timing window between resource access and modification operations, potentially enabling privilege escalation from standard user level to SYSTEM level privileges. The attack vector requires local system access since the vulnerability exists within a service that runs with elevated privileges but is accessible to authenticated users.
The operational impact of this vulnerability extends beyond simple privilege escalation as it provides attackers with persistent access to system resources and capabilities that would otherwise be restricted. Once exploited, the attacker can manipulate telephony-related configurations, access sensitive communication data, or potentially establish persistence mechanisms through modifications to service configurations or registry entries. The vulnerability affects multiple Windows versions including windows 7, windows 8, windows 10, and various server editions where the telephony service is installed and active.
Security professionals should implement immediate mitigations including disabling unnecessary telephony services when not required, applying microsoft security updates that address the synchronization issues, and monitoring for suspicious service access patterns. The mitigation strategy aligns with attack technique mitre att&ck technique t1068 which covers local privilege escalation through race conditions. Organizations should also consider implementing application control policies to restrict execution of unauthorized binaries that might exploit this vulnerability and ensure proper patch management protocols are in place to address similar concurrency issues across other system components.
The root cause analysis reveals that this vulnerability represents a classic synchronization failure pattern where resource management lacks proper atomic operations or critical section handling. Microsoft security response teams have addressed this through patches that implement proper mutex locking mechanisms within the telephony service code, ensuring that shared resources are accessed in a thread-safe manner. System administrators should prioritize applying these updates and conduct regular vulnerability assessments to identify similar race condition patterns in other system services that may present comparable risks.