CVE-2026-70143 in Windows
Summary
by MITRE • 10/14/2026
Heap-based buffer overflow in Windows Network File System allows an authorized attacker to execute code locally.
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Analysis
by VulDB Data Team • 10/14/2026
The vulnerability described constitutes a heap-based buffer overflow within the Microsoft Windows Network File System, commonly referred to as NFS. This component is responsible for facilitating file sharing and access across networked environments using the NFS protocol standards. The core technical flaw lies in how the service handles memory allocation and data validation during the processing of specific NFS requests or packets. When an attacker sends a specially crafted request containing oversized or malformed data, the application fails to properly validate the length of the input against the allocated buffer size on the heap. This lack of boundary checking allows the excess data to overwrite adjacent memory locations that are critical for program execution flow and security structures such as exception handlers or function pointers.
From an operational perspective, this vulnerability is particularly dangerous because it can be exploited by an authenticated user who has legitimate access to the NFS share but possesses insufficient privileges to execute arbitrary code directly. By leveraging the heap overflow, the attacker can achieve remote code execution with the same privilege level as the service running the NFS component, which typically operates under high-privilege system accounts such as SYSTEM or NETWORK SERVICE. This elevation of privilege allows the attacker to install programs, view, change, or delete data, and create new accounts with full administrative rights on the affected host. The impact extends beyond a single machine if the compromised server is part of an active directory domain, potentially allowing lateral movement across the network infrastructure.
In terms of industry classification standards, this vulnerability aligns closely with CWE-122: Heap-based Buffer Overflow and CWE-787: Out-of-bounds Write in the Common Weakness Enumeration framework. These classifications highlight the fundamental memory safety error where data is written beyond the allocated heap boundaries. Furthermore, from a tactical standpoint within the MITRE ATT&CK matrix, this vulnerability facilitates techniques associated with Privilege Escalation (T1068) and potentially Initial Access if combined with other vectors like T1534: Internal Spearphishing or direct network exploitation depending on authentication requirements. The ability to execute code locally via a network service makes it a critical target for attackers seeking persistent access within an enterprise environment.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. Microsoft has released security updates that patch this specific flaw by enforcing stricter input validation and bounds checking within the NFS server implementation. Organizations should prioritize applying these cumulative security patches to all systems running vulnerable versions of Windows with the NFS role enabled. Additionally, network segmentation can reduce exposure by restricting access to NFS services only from trusted subnets or authorized clients using firewall rules. For environments where NFS is not strictly required, disabling the feature entirely reduces the attack surface significantly. Regular vulnerability scanning and monitoring for anomalous memory usage patterns in system logs can also aid in early detection of exploitation attempts before full compromise occurs.