Description

Use after free in Windows Telephony Service allows an authorized attacker to elevate privileges locally.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.0",
  "pubDate": "2026-08-11T17:18:23.540Z",
  "pubdate": "2026-08-11T17:18:23.540Z",
  "executiveSummary": "A use-after-free vulnerability exists within the Windows Telephony Service, affecting local Microsoft Windows environments. This security flaw stems from improper management of object lifecycles in memory, allowing a locally authenticated attacker to manipulate dangling pointers following the deallocation of a specific resource. Successful exploitation of this vulnerability compromises the integrity and confidentiality of the host operating system, culminating in local privilege escalation. By leveraging this memory corruption vector, a low-privileged user can execute arbitrary code with elevated privileges, potentially achieving SYSTEM-level access depending on the context of the vulnerable service process. Attack prerequisites require the adversary to have initial local access to the target system and authorization to interact with the telephony service interface. The risk implication is severe, as privilege escalation vulnerabilities are frequently chained with other exploits to bypass security boundaries, facilitate lateral movement, or establish persistent control over compromised endpoints. Mitigation relies strictly on applying vendor-supplied security updates designed to correct memory management routines within the affected component.",
  "technicalDetails": "The vulnerability is classified as a use-after-free memory corruption flaw residing in the Windows Telephony Service component. A use-after-free condition occurs when an application continues to use a pointer after the memory object it references has been freed or deallocated. In the context of the Windows Telephony Service, this typically transpires during complex state transitions or inter-process communication handling where object references are improperly tracked across multiple threads or execution contexts.\nThe root cause is rooted in inadequate reference counting or synchronization flaws within the vulnerable component's heap management implementation. When a specific telephony object is released, internal references to the memory address are not reliably nullified or invalidated. Consequently, if an authorized attacker induces a sequence of operations that triggers the re-use of the dangling pointer, they can redirect execution flow or manipulate application data structures residing at the target memory location.\nThe attack flow proceeds as follows: First, the local attacker establishes interaction with the Windows Telephony Service via documented application programming interfaces or local procedure calls. Second, the attacker crafts a specific sequence of requests designed to allocate, reference, and subsequently deallocate a targeted object within the service heap, intentionally leaving a dangling pointer intact. Third, the attacker performs heap feng shui or memory grooming techniques to allocate controlled payload data into the recently freed memory chunk. Finally, by triggering an operation that accesses the dangling pointer, the application inadvertently interacts with the attacker-controlled data, resulting in the execution of arbitrary code.\nBecause the Windows Telephony Service executes with high privileges, successfully redirecting execution flow via this use-after-free condition enables the attacker to inherit the security context of the service process. This facilitates local privilege escalation, allowing the execution of arbitrary binaries or administrative commands on the underlying operating system. The vulnerability requires local authentication and local execution capabilities, meaning remote network exposure is not a direct vector unless combined with a separate remote code execution vulnerability."
}