Description

Heap-based buffer overflow in Windows Cloud Files Mini Filter Driver allows an authorized attacker to elevate privileges locally.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.8",
  "pubDate": "2026-08-11T17:18:29.750Z",
  "pubdate": "2026-08-11T17:18:29.750Z",
  "executiveSummary": "A heap-based buffer overflow vulnerability exists within the Windows Cloud Files Mini Filter Driver, presenting a significant security risk to local environments.\nThe vulnerability allows an authorized local attacker to execute arbitrary code with elevated privileges, potentially leading to a complete compromise of the affected operating system.\nThe affected product is the Windows Cloud Files Mini Filter Driver, which is a core kernel-mode component responsible for managing cloud file synchronization and virtualization.\nSuccessful exploitation of this flaw requires local access and prior authorization, meaning an attacker must already possess execution capabilities on the target machine before attempting to elevate privileges.\nFrom a risk perspective, this vulnerability bridges the gap between standard user execution and kernel-level control, enabling threat actors to bypass security boundaries, disable endpoint detection mechanisms, and maintain persistent, high-privilege access.\nRemediation requires applying the official vendor-supplied security updates designated for the affected driver component.",
  "technicalDetails": "The vulnerability is rooted in an improper bounds check within the heap memory management logic of the Windows Cloud Files Mini Filter Driver.\nKernel-mode drivers interact closely with user-mode applications through Input/Output Control (IOCTL) requests and custom communication ports, where data buffers are frequently passed across the user-kernel boundary.\nThe root cause stems from the driver allocating an insufficient heap buffer size when processing specific requests or failing to properly validate the size parameters supplied within input structures.\nWhen the driver attempts to copy data into the inadequately sized heap-allocated buffer, a heap-based buffer overflow occurs, resulting in the corruption of adjacent heap metadata and critical kernel objects.\nTo exploit this vulnerability, an authorized local attacker formulates a malicious payload delivered via standard driver communication channels, interacting directly with the vulnerable Windows Cloud Files Mini Filter Driver.\nUpon receiving the malformed input, the driver processes the request and writes data beyond the allocated heap boundary.\nBy carefully crafting the input data and manipulating the kernel heap layout, the attacker can overwrite adjacent heap chunks containing function pointers, object headers, or security context structures.\nThis memory corruption is subsequently leveraged to hijack the control flow of the kernel, redirecting execution to attacker-supplied shellcode or invoking existing kernel APIs in an unauthorized manner.\nBecause the driver operates in kernel mode (Ring 0), successful control flow redirection grants the attacker kernel-level execution privileges.\nThe attack flow requires local authentication and appropriate permissions to interact with the driver interface, negating the need for network exposure.\nFollowing successful exploitation, the post-exploitation impact includes the elevation of the attacker's process token to NT AUTHORITY\\SYSTEM, allowing the execution of arbitrary commands, tampering with system configurations, evasion of security controls, and full control over the underlying host."
}