CVE-2026-50386 in Windows
Summary
by MITRE • 07/14/2026
Heap-based buffer overflow in Windows NTFS allows an unauthorized attacker to execute code locally.
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Analysis
by VulDB Data Team • 07/15/2026
This vulnerability represents a critical heap-based buffer overflow condition within the Windows NT filesystem implementation that enables local privilege escalation through arbitrary code execution. The flaw occurs when the ntfs.sys kernel driver processes malformed input data structures during file system operations, specifically when handling compressed files or directory entries with excessive metadata. The vulnerability stems from insufficient bounds checking in memory allocation routines where attacker-controlled data can overwrite adjacent heap memory regions, potentially corrupting critical data structures or function pointers.
The technical exploitation involves crafting malicious NTFS file system structures that trigger the buffer overflow during normal file operations such as file creation, modification, or directory traversal. When the vulnerable driver attempts to process these malformed inputs, it allocates heap memory without proper validation of input size limits, allowing subsequent writes to exceed allocated buffer boundaries and overwrite adjacent memory segments. This memory corruption can be leveraged to redirect execution flow through overwrite of return addresses or virtual function table pointers, enabling code execution with kernel-level privileges.
The operational impact of this vulnerability extends beyond simple local privilege escalation as it provides attackers with complete system compromise capabilities without requiring network connectivity or remote access. The attack vector is particularly concerning because it operates entirely within the local file system context, making detection more challenging through traditional network-based monitoring systems. Successful exploitation can result in full system takeover, data exfiltration, persistence mechanisms installation, and privilege escalation to SYSTEM level access.
Mitigation strategies should focus on immediate patch deployment from microsoft security updates that include heap memory validation fixes and enhanced input sanitization within the ntfs.sys driver. Additional protective measures include implementing kernel mode code integrity checks through windows defender application control or similar technologies, disabling unnecessary file system features such as compression when not required, and monitoring for anomalous file system operations through endpoint detection and response solutions. Organizations should also consider applying security configuration baselines that restrict local file system access where possible and implement comprehensive logging of file system activities to detect potential exploitation attempts.
This vulnerability aligns with CWE-121 heap-based buffer overflow category and maps to attack patterns within the attack tree that include privilege escalation and code execution in kernel space. The flaw demonstrates typical characteristics of windows kernel vulnerabilities that leverage memory corruption techniques to achieve unauthorized system access, similar to other well-known ntfs-related exploits documented in various security advisories and threat intelligence reports.