CVE-2026-76486 in NX-OS
Summary
by MITRE • 10/07/2026
A vulnerability in the VXLAN Operation, Administration, and Maintenance (OAM) feature of Cisco NX-OS Software, known as NGOAM, could allow an unauthenticated, remote attacker to execute arbitrary code with root privileges or cause a Denial-of-Service (DoS) on an affected device.
This vulnerability is due to improper input validation of IP traffic when the NGOAM feature is enabled. An attacker could exploit this vulnerability by sending crafted packets to an IP interface on an affected device. A successful exploit could allow the attacker to execute arbitrary code with root privileges and could cause process crashes resulting in a reload and DoS condition.
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Analysis
by VulDB Data Team • 10/07/2026
The Cisco NX-OS Software contains a critical security flaw within its VXLAN Operation, Administration, and Maintenance feature, commonly referred to as NGOAM. This vulnerability stems from insufficient input validation mechanisms when processing Internet Protocol traffic destined for the NGOAM service interface. The core technical deficiency lies in the failure of the software to properly sanitize or verify the structure and content of incoming packets before they are processed by the underlying system routines. Because this feature is designed to facilitate network diagnostics and management over VXLAN tunnels, it must accept a wide variety of packet formats from potentially untrusted sources within the data center fabric. The lack of rigorous boundary checks allows an attacker to craft maliciously formatted packets that trigger memory corruption or logic errors during parsing operations. This specific flaw aligns with CWE-20 Improper Input Validation and is often associated with CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer, as improper handling can lead to buffer overflows or out-of-bounds writes depending on the exact nature of the crafted payload.
The operational impact of this vulnerability is severe due to its potential for remote code execution and service disruption. An unauthenticated attacker positioned at any point in the network path that allows access to the affected IP interface can exploit this flaw by sending specially constructed packets. Upon successful exploitation, the attacker gains the ability to execute arbitrary commands with root-level privileges on the compromised device. This level of access effectively compromises the integrity, confidentiality, and availability of the entire system, allowing for complete control over network infrastructure components such as switches or routers running NX-OS. Furthermore, even if code execution is not achieved, a successful exploit can cause critical process crashes within the operating system. These crashes typically result in an automatic reload of the device, leading to a significant Denial-of-Service condition that disrupts network connectivity and service availability for all users relying on the affected infrastructure.
From a threat modeling perspective, this vulnerability is classified under MITRE ATT&CK technique T1203 Exploitation for Client Execution or potentially T1498 Network Denial of Service depending on the exploit variant used. The attack vector is remote and requires no prior authentication, which significantly lowers the barrier to entry for malicious actors. This characteristic places it in a high-severity category within vulnerability management frameworks because it can be exploited by automated tools without human interaction or specific user privileges. The ability to escalate to root privileges means that once initial access is gained through this flaw, subsequent lateral movement and persistence mechanisms become trivially easy to implement, further amplifying the risk to enterprise networks.
Mitigation strategies must focus on both immediate remediation and long-term architectural hardening. Cisco has released software updates that patch the input validation logic within the NGOAM feature; administrators should apply these patches as soon as possible to close the security gap. In environments where upgrading is not immediately feasible, network segmentation policies can be implemented to restrict access to VXLAN OAM interfaces from untrusted networks or hosts. Additionally, enabling strict ingress filtering and deploying intrusion prevention systems configured with signatures for this specific vulnerability can help detect and block malicious traffic before it reaches the vulnerable NX-OS devices. Regular auditing of configuration settings related to management plane protocols ensures that unnecessary services are disabled if they do not align with operational requirements, thereby reducing the attack surface available to potential adversaries.