CVE-2026-50309
Summary
by MITRE • 07/14/2026
Heap-based buffer overflow in Windows NTFS allows an authorized attacker to execute code locally.
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Analysis
by VulDB Data Team • 07/14/2026
This vulnerability represents a critical heap-based buffer overflow flaw within the Windows NTFS file system implementation that enables authenticated local attackers to achieve arbitrary code execution on affected systems. The technical nature of this vulnerability stems from improper input validation and memory management practices within the ntfs.sys kernel driver responsible for handling NTFS file system operations. When legitimate user processes interact with NTFS volumes through specific file system operations, particularly those involving malformed or specially crafted file attributes, directory entries, or volume metadata structures, the kernel driver fails to properly bounds-check heap-allocated buffers before copying data into them. This fundamental flaw allows an attacker who has already established a valid user account on the target system to manipulate input parameters in such a way that exceeds the allocated buffer boundaries, resulting in memory corruption that can be exploited to overwrite critical memory locations including return addresses, function pointers, or other control structures within the kernel execution context.
The operational impact of this vulnerability extends beyond simple privilege escalation as it provides attackers with a direct pathway to kernel-level code execution without requiring additional exploitation techniques or bypass mechanisms. Once successfully exploited, the attacker gains complete control over the target system, effectively elevating their privileges from standard user level to SYSTEM level access, which grants unrestricted administrative capabilities including full read/write access to all files and directories, modification of system configurations, installation of malicious software, and potential establishment of persistent backdoors. The vulnerability's local nature means that attackers do not require network connectivity or remote access capabilities to exploit it, making detection more challenging as the attack occurs within the boundaries of legitimate user sessions.
The exploitation process typically involves leveraging specific NTFS file system operations such as creating or modifying files with maliciously crafted attributes, manipulating directory structures in ways that trigger buffer overflows during internal processing, or exploiting race conditions in file system metadata handling. Attackers often employ techniques such as heap spraying to increase exploit reliability and may utilize existing kernel exploitation frameworks or custom shellcode generation to achieve their objectives. This vulnerability aligns with CWE-121 heap-based buffer overflow categories and maps to several ATT&CK tactics including privilege escalation, defense evasion, and persistence through the ability to gain SYSTEM-level access and manipulate system processes. Microsoft typically addresses such vulnerabilities through security patches that correct memory management logic within the ntfs.sys driver, implementing proper bounds checking mechanisms, and often incorporating additional security features like kernel address space layout randomization and exploit protection mechanisms.
Organizations should prioritize immediate patch deployment for this vulnerability as it represents a significant risk to system integrity and data confidentiality. System administrators must ensure comprehensive testing of patches in controlled environments before widespread deployment to avoid potential service disruptions. Additional mitigations include implementing least privilege access controls, monitoring for unusual file system activity patterns, and maintaining regular security assessments of file system operations. The vulnerability demonstrates the critical importance of kernel-level security validation and proper input sanitization practices in operating system components that handle user-provided data, as even authenticated users with legitimate access can potentially exploit such flaws to compromise entire systems.