CVE-2026-50402 in Windows
Summary
by MITRE • 07/14/2026
Incorrect conversion between numeric types in Windows NTFS allows an authorized attacker to elevate privileges locally.
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Analysis
by VulDB Data Team • 07/15/2026
This vulnerability represents a critical type conversion flaw within the Windows NTFS file system implementation that enables local privilege escalation for authenticated users. The issue stems from improper handling of numeric data types during file system operations, specifically when converting between different integer sizes or representations during metadata processing. When an attacker with legitimate user credentials performs certain file system operations, the system fails to properly validate or convert numeric values, creating a path for unauthorized privilege elevation.
The technical root cause involves CWE-191, which addresses integer underflow and overflow conditions, combined with CWE-194, which deals with unexpected sign extension in numeric conversions. During NTFS file system processing, when the kernel handles file attributes, directory entries, or metadata structures, it performs implicit type conversions between different numeric representations that may not properly account for value ranges or signed/unsigned distinctions. This flaw manifests when file system operations attempt to convert 32-bit values to 64-bit representations or vice versa without proper bounds checking.
The operational impact of this vulnerability allows an attacker to exploit the type conversion error by crafting specific file system operations that manipulate numeric values in ways that trigger the improper conversion logic. Once triggered, the vulnerability can enable privilege escalation from standard user level to SYSTEM level access, providing complete control over the affected system. The attack requires local authentication and execution privileges but does not require network access or remote exploitation capabilities.
Security professionals should implement immediate mitigations including applying Microsoft security patches through Windows Update, monitoring for unusual file system operations that might indicate exploitation attempts, and implementing least privilege principles to limit potential damage from successful attacks. Organizations should also consider deploying endpoint detection and response solutions that can identify suspicious numeric conversion patterns within file system APIs. The vulnerability aligns with ATT&CK technique T1068 which covers local privilege escalation through kernel exploits, and T1547 which addresses registry and service modifications that may occur during privilege escalation operations.
This flaw demonstrates the importance of rigorous input validation and type safety in kernel-level code implementations, particularly within file system drivers where numeric conversions are frequent. The vulnerability highlights how seemingly minor programming errors in low-level system components can create significant security risks when exploited by determined attackers. Regular security assessments of system call interfaces and kernel-mode drivers should include thorough examination of all numeric conversion operations to prevent similar issues from emerging in the future.