Description

Heap-based buffer overflow in Windows Telephony Service allows an authorized attacker to elevate privileges locally.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.8",
  "pubDate": "2026-08-11T17:18:24.467Z",
  "pubdate": "2026-08-11T17:18:24.467Z",
  "executiveSummary": "This vulnerability is classified as a heap-based buffer overflow affecting the Windows Telephony Service. The flaw arises due to improper bounds checking during the processing of telephony data within the affected component. An authorized local attacker can exploit this weakness to execute arbitrary code with elevated privileges, effectively bypassing standard operating system security controls.\nThe impact of successful exploitation includes complete local privilege escalation, potentially allowing an adversary to attain administrative or system-level access. This poses a severe risk to host integrity and confidentiality, as a compromised local security context facilitates further lateral movement, credential harvesting, and persistence mechanisms across the targeted enterprise environment.\nTarget systems comprise Microsoft Windows installations running the vulnerable Telephony Service. Exploitation requirements dictate that the threat actor must already possess authorized local access to the target host prior to execution. There are no indications of remote network exposure based on the provided input, constraining the attack surface to local vectors.",
  "technicalDetails": "The vulnerability manifests as a heap-based buffer overflow within the Windows Telephony Service. The root cause is attributed to insufficient validation of input sizes when allocating and writing data to dynamic memory buffers managed by the service. When specifically crafted input is supplied to the vulnerable function, the amount of data written exceeds the allocated boundary of the heap chunk, leading to memory corruption.\nExploitation of this heap corruption vulnerability requires the attacker to interact locally with the Windows Telephony Service APIs or exposed inter-process communication interfaces. The step-by-step attack flow begins with the local attacker authenticating or interacting with the service using valid system calls or application programming interfaces. The attacker then submits malformed parameters designed to trigger the unsafe memory copy operation.\nUpon processing the malicious payload, the heap buffer overflows, overwriting adjacent heap metadata or critical function pointers residing in the heap memory space. By carefully engineering the size and content of the overflowing data, an attacker can manipulate heap layout dynamics to achieve arbitrary code execution. Because the Windows Telephony Service typically executes within a privileged context, successfully diverting execution flow grants the attacker the privileges associated with the service process.\nThe vulnerable component is the Windows Telephony Service. Authentication requirements mandate that the attacker is an authorized user capable of communicating with the service locally. Privilege requirements are low prior to exploitation, as standard local user rights are sufficient to interface with the vulnerable functionality. Network exposure is strictly local, precluding unauthenticated remote exploitation over network sockets without prior local access or a chained remote-to-local entry vector."
}