Description

Out-of-bounds read in Windows Win32K allows an authorized attacker to disclose information locally.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "5.5",
  "pubDate": "2026-08-11T17:18:26.353Z",
  "pubdate": "2026-08-11T17:18:26.353Z",
  "executiveSummary": "An out-of-bounds read vulnerability exists within the Windows Win32K component, which can be leveraged by an authorized local attacker to achieve unauthorized information disclosure. This security flaw compromises memory confidentiality by potentially exposing sensitive kernel-level data to user-mode processes. The affected systems encompass vulnerable versions of the Microsoft Windows operating system utilizing the Win32K subsystem. Risk implications center around the potential leakage of critical kernel memory structures, which sophisticated adversaries frequently chain with elevation of privilege or other memory corruption exploits to bypass defensive security controls such as Kernel Address Space Layout Randomization. Exploitation of this vulnerability requires local access to the target machine and that the attacker possesses authorization or execution capabilities within the local environment. No specific network exposure or remote attack vectors are indicated, classifying this strictly as a local vector requiring authenticated execution context.",
  "technicalDetails": "The vulnerability resides in the Windows Win32K graphics and windowing subsystem, specifically within memory management routines handling data reads. The root cause stems from an out-of-bounds read condition, where the component fails to properly validate index boundaries or size parameters before accessing memory buffers. When an application submits specific malicious or malformed requests to the Win32K driver, the subsystem reads past the allocated buffer boundary, retrieving adjacent kernel memory contents.\nThe attack flow proceeds as follows: First, the authorized attacker establishes execution on the target Windows system within a local security context. Second, the attacker invokes specific Win32 system calls or interacts with vulnerable graphical user interface objects handled by the Win32K kernel driver. Third, the crafted input or API invocation triggers the flawed memory read operation within the kernel space, causing the driver to read out-of-bounds data from kernel heap or pool memory. Finally, the extracted information is returned to the user-mode application or exposed through side-channel behaviors, allowing the attacker to inspect sensitive kernel addresses or data structures.\nThe vulnerable component is the Win32K kernel-mode driver responsible for graphical rendering and window management functions. Privilege requirements dictate that the attacker must be locally authenticated on the target host. Network exposure is non-existent, as the flaw cannot be triggered remotely. The post-exploitation impact is primarily focused on information disclosure, yielding unauthorized access to kernel memory layouts. This leaked data significantly aids attackers in formulating reliable multi-stage exploit chains, particularly by defeating kernel-level mitigations designed to randomize memory space and obscure internal kernel structures."
}