CVE-2026-49792 in Windows
Summary
by MITRE • 07/14/2026
Numeric truncation error in Windows Resilient File System (ReFS) allows an authorized attacker to execute code locally.
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Analysis
by VulDB Data Team • 07/14/2026
The vulnerability under examination involves a numeric truncation error within the Windows Resilient File System implementation that enables local code execution by authorized attackers. This flaw exists in the way ReFS handles certain numerical operations during file system processing, specifically when dealing with large integer values that exceed the capacity of standard data types. The issue manifests when the file system performs arithmetic operations or comparisons using variables that are susceptible to overflow conditions, creating opportunities for malicious code injection through carefully crafted file system operations.
The technical root cause of this vulnerability stems from improper handling of numeric data types within ReFS kernel components responsible for file metadata processing and storage allocation management. When an attacker with legitimate access to the system manipulates file attributes or performs operations that trigger specific numerical calculations, the truncation error occurs during type conversion processes. This typically happens when 64-bit values are cast to 32-bit representations without proper bounds checking or validation mechanisms. The CWE-190 classification applies here as this represents an integer overflow condition where the system fails to properly handle numeric boundaries during mathematical operations.
The operational impact of this vulnerability extends beyond simple code execution capabilities, as it provides attackers with a mechanism to escalate privileges within the file system context. Authorized users can leverage this flaw to inject malicious payloads that execute with the privileges of the ReFS subsystem, potentially compromising entire storage volumes and data integrity. The attack vector requires local system access but does not necessitate network connectivity or external exploitation methods, making it particularly dangerous in environments where administrative privileges are frequently used. This aligns with ATT&CK technique T1068 which covers privilege escalation through local system exploitation.
Mitigation strategies should focus on implementing proper input validation and bounds checking within ReFS kernel components, ensuring that all numerical operations include appropriate overflow protection mechanisms. System administrators should deploy the latest Windows updates and security patches from Microsoft that address this specific vulnerability while also considering network segmentation policies to limit potential attack surfaces. Additional protective measures include monitoring for anomalous file system behavior and implementing least privilege access controls to minimize the impact of successful exploitation attempts. The vulnerability demonstrates the critical importance of robust numerical handling in kernel-level components and emphasizes the need for comprehensive security testing of storage subsystems against edge case scenarios.