CVE-2026-76471 in NX-OS Software
Summary
by MITRE • 10/07/2026
A vulnerability in the NX-API feature of Cisco NX-OS Software could allow an unauthenticated, remote attacker to execute arbitrary code with root privileges or cause a denial of service (DoS) condition on an affected device.
The vulnerability is due to insufficient input validation of data that is sent to the NX-API. An attacker could exploit this vulnerability by sending a crafted HTTP request to the NX-API of an affected device. A successful exploit could allow the attacker to execute arbitrary code with root privileges and could cause process crashes, which could result in a reload of the device and a DoS condition.
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Analysis
by VulDB Data Team • 10/07/2026
The identified security flaw resides within the Network eXtensible API (NX-API) subsystem of Cisco NX-OS Software, presenting a critical risk to network infrastructure integrity. This vulnerability stems from insufficient input validation mechanisms when processing data transmitted via HTTP requests directed at the NX-API interface. The core technical deficiency involves the failure to properly sanitize or validate specific fields within incoming request payloads before they are processed by the underlying system components. Because NX-API serves as a primary programmatic interface for managing and configuring network devices, it is frequently exposed to management networks where automated scripts and orchestration tools interact with the operating system. The lack of rigorous boundary checks on input data allows an unauthenticated remote attacker to inject malicious content that bypasses expected parsing logic, leading to memory corruption or logical errors within the application layer.
From a technical perspective, this flaw is classified under CWE-20 as Improper Input Validation and aligns with ATT&CK technique T1190, which describes exploiting publicly facing applications in initial access scenarios. The vulnerability enables two distinct attack vectors depending on the nature of the crafted HTTP request sent by the attacker. In one scenario, the malformed input triggers a buffer overflow or similar memory corruption error that allows for arbitrary code execution with root privileges. This grants the adversary full control over the operating system, enabling them to install backdoors, modify configurations, pivot to other network segments, and exfiltrate sensitive data without detection by standard authentication mechanisms. In another scenario, the invalid input causes a segmentation fault or critical process crash within the NX-API service daemon.
The operational impact of this vulnerability is severe due to its unauthenticated nature and high privilege level. If exploited for code execution, an attacker gains complete administrative control over the network device, effectively compromising the entire infrastructure managed by that switch or router. This can lead to widespread network disruption, data breaches, and lateral movement across the enterprise environment. Conversely, if exploited for denial of service, the resulting process crashes force a reload of the affected device. Since NX-API is often integral to automated management workflows, such instability disrupts ongoing configuration changes and monitoring activities. The need for a device reload introduces significant downtime, impacting network availability and potentially causing cascading failures in high-availability clusters if multiple nodes are targeted simultaneously.
Mitigation strategies must prioritize immediate patching of the affected Cisco NX-OS software versions to address the input validation deficiencies within the NX-API module. Organizations should also implement strict access control lists (ACLs) to restrict HTTP traffic destined for the NX-API interface, allowing connections only from trusted management stations or specific IP ranges. Additionally, deploying network intrusion prevention systems with signatures capable of detecting malformed HTTP requests targeting Cisco devices can provide a layer of defense in depth. It is critical to disable unused API endpoints and enforce strong authentication mechanisms where possible, although this vulnerability specifically affects unauthenticated access paths, making patching the most effective remediation step until alternative architectural controls are fully implemented.