CVE-2026-83867 in Windows
Summary
by MITRE • 10/14/2026
Heap-based buffer overflow in Windows Push Notifications allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability described involves a heap-based buffer overflow within the Windows Push Notification service, specifically affecting components responsible for handling incoming notification payloads or metadata. This class of flaw typically arises when the application fails to properly validate the length of user-supplied input before copying it into a fixed-size memory buffer allocated on the heap. In this context, an attacker who has already gained authorized access to the system can craft maliciously formatted push notifications that exceed the expected bounds of the target buffer. When the vulnerable component processes these oversized inputs, data is written beyond the allocated boundaries, corrupting adjacent memory structures such as heap metadata or function pointers stored nearby in memory.
The operational impact of this vulnerability is significant because it enables local privilege escalation from a standard user account to that of SYSTEM or another high-privilege context. By carefully controlling the overflow payload, an attacker can overwrite critical control data within the heap structure, potentially achieving arbitrary code execution during subsequent memory operations such as allocation or deallocation. This allows the malicious actor to bypass security mechanisms like User Account Control (UAC) and execute commands with elevated permissions, effectively taking full control of the compromised system. The ability to escalate privileges locally makes this a critical threat for any environment where multiple users share access to Windows devices, particularly in enterprise settings where lateral movement is a primary concern for attackers.
From a classification perspective, this vulnerability aligns with CWE-122, which denotes heap-based buffer overflow, and falls under the ATT&CK technique T1068, representing Exploitation for Privilege Escalation. The attack vector requires local access or valid credentials, categorizing it as an internal threat that exploits trust relationships within the operating system's authentication framework. Mitigation strategies primarily involve applying vendor-provided security patches that address the input validation logic in the push notification service components. Organizations should ensure timely deployment of these updates across all endpoints to close this privilege escalation path. Additionally, implementing strict application whitelisting and monitoring for unusual process creation events can help detect exploitation attempts even if patching is delayed, thereby reducing the window of opportunity for attackers leveraging this flaw.