CVE-2026-50669 in Windows
Summary
by MITRE • 07/14/2026
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 • 07/14/2026
A race condition vulnerability exists within the Windows Telephony Service that enables authenticated local attackers to achieve privilege escalation through improper synchronization of shared resources during concurrent execution. This flaw resides in the telephony service component responsible for managing telephone connections and related system functions, where multiple threads or processes access common resources without adequate locking mechanisms or synchronization protocols. The vulnerability manifests when the service handles concurrent operations involving shared memory segments, file handles, or registry entries that control telephony functionalities. When multiple execution paths attempt to modify or access these shared resources simultaneously, the timing of their execution can lead to unpredictable behavior where one thread's operations interfere with another's, potentially allowing an attacker to manipulate system states in unintended ways.
The technical implementation of this race condition involves the Windows Telephony Service failing to properly implement mutex locks, critical sections, or other synchronization primitives when managing concurrent access to shared resources. Attackers can exploit this by creating multiple simultaneous processes or threads that attempt to modify the same telephony service configuration elements or system resources. This creates opportunities where an attacker-controlled process can overwrite legitimate system data with malicious content, potentially manipulating privilege levels or access controls within the telephony service context. The vulnerability specifically affects systems where the telephony service runs with elevated privileges, making local privilege escalation possible through careful manipulation of shared resource access patterns.
The operational impact of this vulnerability extends beyond simple privilege escalation as it provides attackers with potential access to sensitive telephony functions and system resources that are typically restricted. An attacker with local user privileges can leverage this race condition to gain administrative or SYSTEM-level access to the Windows system, potentially enabling further lateral movement or persistence within the network environment. The attack vector requires local system access and authentication, making it less suitable for remote exploitation but still dangerous in environments where local compromise is possible. This vulnerability aligns with CWE-362 which specifically addresses race conditions involving concurrent execution and improper synchronization, and maps to ATT&CK technique T1068 related to exploit for privilege escalation.
Mitigation strategies for this vulnerability require immediate system updates through Microsoft security patches that address the specific synchronization issues within the Windows Telephony Service. System administrators should ensure all Windows systems are kept up-to-date with the latest security releases and apply relevant hotfixes promptly. Additional protective measures include implementing least privilege principles for telephony service accounts, monitoring for unusual concurrent process execution patterns related to telephony services, and conducting regular security audits of system configurations. Network segmentation and access control policies should limit local system access to reduce attack surface. The vulnerability demonstrates the critical importance of proper synchronization mechanisms in multi-threaded applications, particularly those handling sensitive system functions, and underscores the necessity of following secure coding practices that prevent race conditions through appropriate locking and resource management protocols.