Description

Stack-based buffer overflow in Windows Win32K allows an authorized attacker to elevate privileges locally.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.8",
  "pubDate": "2026-08-11T17:18:38.390Z",
  "pubdate": "2026-08-11T17:18:38.390Z",
  "executiveSummary": "This vulnerability is a stack-based buffer overflow affecting the Windows Win32K component, which can be leveraged by an authorized local attacker to achieve local privilege escalation. The flaw resides within kernel-mode graphics and windowing subsystems that process input and memory structures without adequate bounds checking. Successful exploitation allows malicious actors to execute arbitrary code with elevated privileges, typically yielding SYSTEM-level access on the target operating system. The risk implication is severe, as a successful exploit compromises the entire operating system integrity, enabling attackers to bypass security boundaries, install malicious drivers, access sensitive data, or modify system configurations. Exploitation requires the attacker to already possess authorized local access to the target system, meaning the attack vector is strictly local and non-network-exposed. While remote exploitation is not possible through this specific vector, local users, including standard user accounts or compromised service accounts, can exploit the weakness to escalate their privileges to the highest level available. Remediation relies on applying vendor-supplied patches that correct memory handling and bounds validation within the affected Win32K component.",
  "technicalDetails": "The vulnerability is classified as a stack-based buffer overflow occurring within the Windows Win32K kernel-mode driver component. The root cause stems from insufficient validation of input lengths and memory boundaries when data is copied onto the kernel stack. Specifically, when user-mode or kernel-mode routines process specific windowing messages, graphic structures, or system calls, the vulnerable function fails to adequately verify that the destination buffer allocated on the stack is large enough to contain the incoming source data. An authorized attacker initiates the attack flow by executing a crafted application or script on the target host. This payload interacts with the Win32K subsystem through standard graphical device interface (GDI) or user interface system calls, supplying maliciously malformed input designed to exceed the allocated stack buffer size. As the Win32K component processes the oversized data, a memory corruption condition occurs, overwriting adjacent stack memory, including critical control data such as saved frame pointers and return addresses. By carefully crafting the input payload, the attacker can hijack the execution flow of the kernel-mode thread, redirecting execution to malicious shellcode or leveraging return-oriented programming (ROP) chains. The affected component is the Win32K subsystem, operating within the Windows kernel address space. Authentication requirements are minimal regarding exploitation, as the attacker only needs valid local execution privileges to interact with the Win32K API. Privilege requirements are limited to an authorized local user context, requiring no prior administrative rights to trigger the vulnerability. The network exposure is strictly local, as Win32K interfaces are not directly exposed to remote network stacks without intermediary application layers or remote desktop sessions. Post-exploitation impact results in full local privilege escalation, allowing the attacker to subvert kernel-level security controls, disable Endpoint Detection and Response (EDR) agents, create persistence mechanisms, and compromise the confidentiality, integrity, and availability of the entire operating system."
}