Description

Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Telephony Service allows an authorized attacker to elevate privileges locally.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.0",
  "pubDate": "2026-08-11T17:18:24.100Z",
  "pubdate": "2026-08-11T17:18:24.100Z",
  "executiveSummary": "A local privilege escalation vulnerability exists within the Windows Telephony Service, specifically categorized as a concurrent execution using a shared resource with improper synchronization, or a race condition.\nThis security flaw enables an authorized local attacker to elevate their execution privileges on the targeted system.\nThe affected product is the Windows Telephony Service.\nThe primary risk implication is the potential for an authenticated, low-privileged local user to execute arbitrary code or commands with higher privileges, thereby compromising the security boundary of the host operating system.\nSuccessful exploitation requires the attacker to have local access to the system and authenticated capabilities, alongside the ability to execute concurrent operations to trigger the timing window associated with the improper synchronization.\nNo specific version numbers or external exploitation requirements beyond local authentication are detailed in the provided context.",
  "technicalDetails": "The vulnerability stems from improper synchronization during concurrent execution involving a shared resource within the Windows Telephony Service.\nThe vulnerable component is the Windows Telephony Service, which handles telephony-related API calls and operations within the operating system.\nThe root cause of the issue is a race condition, occurring when multiple threads or processes access and manipulate a shared resource without adequate locking or serialization mechanisms, leading to unpredictable behavior and potential security boundary violations.\nThe authentication requirement is an authorized user, and the privilege requirement is local access to the system.\nNetwork exposure is strictly local, as the attack vector requires local presence on the target machine rather than remote network access.\nThe exploitation method involves an attacker leveraging the synchronization flaw by initiating concurrent requests or operations that target the shared resource managed by the Windows Telephony Service.\nThe attack flow proceeds as follows: First, the local attacker establishes execution capability on the system as an authorized, unprivileged user. Second, the attacker interacts with the Windows Telephony Service while simultaneously generating race condition triggers—rapid, concurrent requests designed to overlap during the critical section where the shared resource is accessed without proper synchronization.\nThird, due to the lack of appropriate synchronization primitives (such as mutexes, critical sections, or semaphores), the service encounters a state anomaly, such as a Time-of-Check to Time-of-Use (TOCTOU) discrepancy or memory corruption condition.\nFinally, the attacker exploits this anomalous state to manipulate system execution flow or gain unauthorized access to privileged operations.\nThe post-exploitation impact includes local privilege escalation, allowing the attacker to transition from a restricted user context to elevated privileges, facilitating further system compromise, persistence, or execution of administrative tasks."
}