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": "2026-08-11T17:18:23.723Z",
  "pubdate": "2026-08-11T17:18:23.723Z",
  "executiveSummary": "A use-after-free vulnerability exists in the Windows Telephony Service, affecting Windows operating systems.\nThe vulnerability allows an authorized local attacker to elevate privileges on the target system.\nThe flaw stems from improper handling of memory objects within the telephony subsystem during specific lifecycle operations, leading to dangling pointers.\nIf successfully exploited, an adversary can execute arbitrary code within the context of a privileged system account, bypassing security boundaries.\nExploitation requires the attacker to have local access and authorization to interact with the telephony service, along with the ability to execute code locally.\nThe risk implication is severe, as local privilege escalation typically facilitates complete system compromise, persistence installation, and defense evasion in multi-user or enterprise environments.\nNo specific software version numbers or CVE identifiers were provided in the input beyond the architectural components described.",
  "technicalDetails": "The root cause of the vulnerability is a use-after-free condition residing in the Windows Telephony Service component responsible for managing telephony sessions and API requests.\nA use-after-free vulnerability occurs when dynamic memory is deallocated but the application retains a pointer to that memory address. If the pointer is subsequently dereferenced, unpredictable behavior, memory corruption, or arbitrary code execution can occur.\nIn the context of the Windows Telephony Service, improper synchronization or flawed object reference counting during the teardown or processing of telephony sessions leads to a dangling pointer.\nAn authorized local attacker initiates a sequence of specially crafted inter-process communication or API calls to the telephony service, forcing the target object to be freed while maintaining a valid reference to the stale memory address.\nThe attacker then performs heap manipulation—commonly known as heap spraying or grooming—to allocate controlled data into the recently freed memory chunk.\nWhen the telephony service subsequently accesses the dangling pointer, it processes the attacker-controlled data as if it were a legitimate program object or function pointer.\nThis malformed dereference redirects execution flow to attacker-specified payloads or routines.\nBecause the Windows Telephony Service often runs with elevated system privileges, successful exploitation results in the immediate escalation of the attacker's process context to match the service's security token.\nThe attack vector is strictly local, requiring the attacker to possess execution capabilities and local authentication or authorization to interface with the telephony APIs.\nNetwork exposure is not a primary factor unless combined with a remote code execution vector that achieves initial local code execution."
}