CVE-2026-49797 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 • 07/14/2026
This heap-based buffer overflow vulnerability exists within the Windows NTFS file system implementation and represents a critical security flaw that can be exploited by unauthorized attackers to achieve local code execution. The vulnerability stems from insufficient bounds checking when processing certain NTFS file system structures, particularly in how the system handles heap allocations for file metadata and directory entries. When an attacker crafts malicious NTFS structures or manipulates existing file system elements beyond acceptable buffer limits, the system's memory management routines fail to properly validate input parameters, leading to memory corruption that can be leveraged for arbitrary code execution. The flaw operates at the kernel level within the NTFS file system driver, making it particularly dangerous as it can be triggered through normal file system operations such as file creation, modification, or directory traversal activities.
The technical implementation of this vulnerability follows the classic heap overflow pattern where attacker-controlled data is copied into a heap-allocated buffer without proper size validation. This type of flaw falls under the Common Weakness Enumeration category CWE-122 Heap-based Buffer Overflow, which specifically addresses insufficient validation of buffer sizes in heap memory allocations. The vulnerability's exploitation potential is significantly enhanced by the fact that it operates within the kernel space of the Windows operating system, eliminating the need for privilege escalation once successfully triggered. Attackers can leverage this flaw by creating specially crafted NTFS file system structures or manipulating existing files to cause the overflow condition during normal system operations, potentially leading to complete system compromise.
The operational impact of this vulnerability extends beyond simple local code execution as it provides attackers with a persistent foothold within the target system that can be used for further exploitation. The attack surface includes any system running Windows NTFS file systems where an attacker can influence file creation or modification processes, making it particularly relevant in multi-user environments or systems with shared storage resources. This vulnerability can be exploited through various attack vectors including malicious file uploads, compromised network shares, or even physical access scenarios where attackers can manipulate file system structures directly. The exploitation process typically requires minimal privileges and can be automated to target specific Windows versions that contain the vulnerable NTFS implementation, making it a preferred choice for attackers seeking reliable local privilege escalation.
Mitigation strategies for this vulnerability require both immediate patching and operational security measures to reduce attack surface exposure. Microsoft has released security updates addressing this specific heap overflow condition in their NTFS implementations, which should be deployed immediately across all affected systems. Organizations should also implement additional security controls such as enabling kernel address space layout randomization kalsr, disabling unnecessary file system features, and monitoring for suspicious file system activity that could indicate exploitation attempts. Network segmentation and access control measures can help limit the potential impact if an attacker does gain access through this vulnerability. The ATT&CK framework categorizes this type of attack under technique T1068, Local Privilege Escalation, and T1547, Boot or Logon Autostart Execution, as exploitation often leads to persistent system compromise and privilege escalation opportunities for attackers seeking long-term access to target systems.