CVE-2026-62771 in Windows
Summary
by MITRE • 08/11/2026
Heap-based buffer overflow in Windows Cloud Files Mini Filter Driver allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 08/11/2026
This vulnerability resides within the Windows Cloud Files Mini Filter Driver, a component that operates at the kernel level to manage cloud file synchronization operations across various Microsoft services including OneDrive and SharePoint. The heap-based buffer overflow occurs when the driver processes specially crafted input data through its filtering mechanisms, creating an exploitable condition where attacker-controlled data can overwrite adjacent memory regions within the driver's heap allocation. The flaw specifically manifests during the processing of file system notifications and cloud synchronization events, where insufficient bounds checking permits data to be written beyond the allocated buffer boundaries.
The technical implementation of this vulnerability involves the mini filter driver's failure to properly validate input parameters received from user-mode applications or system components during file operation processing. When legitimate user processes interact with cloud-enabled file systems, the driver receives structured data that includes file paths, metadata, and synchronization flags. The overflow occurs because the driver uses insecure memory manipulation functions that do not perform adequate size validation before copying data into fixed-size heap buffers, creating a condition where arbitrary memory locations can be overwritten with attacker-controlled content. This vulnerability is classified under CWE-121 as a heap-based buffer overflow, representing a critical weakness in memory safety practices within kernel-mode components.
The operational impact of this privilege escalation vulnerability enables an authenticated local attacker to execute code with system-level privileges, effectively bypassing standard user access controls and potentially allowing unauthorized system compromise. The attack requires minimal prerequisites since the attacker only needs local login credentials to exploit the vulnerability, making it particularly dangerous in environments where user accounts may be compromised through social engineering or credential theft attacks. Once successfully exploited, the attacker can manipulate system memory to gain full administrative control over the affected Windows system, potentially leading to complete system compromise, data exfiltration, or establishment of persistent backdoors. The exploitation process typically involves crafting malicious file operations that trigger the vulnerable code path, followed by careful memory manipulation to achieve code execution within kernel space.
Mitigation strategies for this vulnerability encompass multiple layers of defensive measures including immediate deployment of Microsoft security updates that address the specific heap overflow condition in the Cloud Files Mini Filter Driver. System administrators should implement the principle of least privilege by restricting local user accounts from performing unnecessary file synchronization operations and by ensuring that only authorized personnel have access to systems running cloud-enabled file services. Network segmentation and monitoring solutions should be deployed to detect anomalous file system activity patterns that might indicate exploitation attempts, particularly around cloud synchronization events and file operation sequences. The vulnerability aligns with ATT&CK technique T1068 which covers local privilege escalation through kernel exploits, and its remediation requires both patch management processes and operational security controls to prevent unauthorized access to vulnerable systems. Organizations should also consider implementing exploit prevention technologies such as Data Execution Prevention (DEP) and Address Space Layout Randomization (ASLR) to make successful exploitation more difficult. Regular vulnerability assessments and penetration testing of cloud integration components can help identify similar memory safety issues in other kernel-mode drivers, while maintaining comprehensive system monitoring to detect potential exploitation attempts through abnormal process behavior or memory access patterns.