Description

Buffer over-read in Windows Win32K allows an authorized attacker to disclose information locally.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "5.5",
  "pubDate": "2026-08-11T17:18:26.697Z",
  "pubdate": "2026-08-11T17:18:26.697Z",
  "executiveSummary": "A local buffer over-read vulnerability has been identified within the Windows Win32K component, which can be exploited by an authenticated local attacker to facilitate unauthorized information disclosure. The flaw stems from improper bounds checking during memory processing operations within the kernel-mode driver, allowing malicious software or an adversary with local system access to read sensitive kernel memory contents. This information disclosure can expose critical operating system structures, potentially bypassing kernel-level mitigations such as KASLR (Kernel Address Space Layout Randomization) and assisting in the formulation of more sophisticated multi-stage privilege escalation attacks. Successful exploitation requires the attacker to possess prior authorization to execute code locally on the target operating system, meaning the vulnerability cannot be leveraged directly via remote network vectors. No specialized privileges beyond standard local execution capabilities are inherently required to trigger the vulnerable code path. The risk implication is moderate to high depending on the sensitivity of the leaked memory pages and the presence of complementary vulnerabilities within the environment. Remediation relies strictly on applying vendor-supplied security updates for the affected Windows platform to correct the out-of-bounds read condition within the Win32K subsystem.",
  "technicalDetails": "The vulnerability resides in the Windows Win32K component, specifically within kernel-mode routines responsible for handling specific graphical or windowing data structures where input length validation is insufficiently enforced. A buffer over-read condition occurs when the affected function reads memory past the designated boundary of an allocated buffer, directly accessing adjacent kernel memory spaces. The root cause is a failure in the internal parsing logic to adequately verify the size constraints of input parameters supplied to the Win32K API before initiating memory read operations. Exploitation of this vulnerability requires an authenticated user to execute a specially crafted application locally on the target Windows system. The attack flow begins with the local process invoking targeted Win32K system calls with manipulated arguments designed to elicit an out-of-bounds read condition within the kernel space. When the vulnerable function processes the malicious input, it reads beyond the legitimate buffer boundaries, capturing adjacent kernel memory contents that may contain sensitive addresses, system states, or cached data. This unauthorized data is then returned to the user-mode caller through standard API output mechanisms or error channels, completing the information disclosure cycle. Because the operation occurs within the win32k.sys driver context, the payload behavior is constrained to passive data retrieval rather than active memory corruption or arbitrary code execution. However, the post-exploitation impact is significant for attackers seeking to defeat security architectures such as KASLR, as the leaked kernel pointers can be leveraged to accurately calculate base addresses of critical kernel modules. This structural intelligence can subsequently be utilized to chain the information disclosure with an arbitrary write or code execution vulnerability to achieve complete system compromise. The vulnerability is entirely local in nature, exhibiting no network exposure, and relies on the execution of custom user-mode code to interact with the kernel-mode graphics subsystem."
}