CVE-2026-76456 in NX-OS Software
Summary
by MITRE • 10/07/2026
As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco NX-OS engineering team has conducted a comprehensive internal security review. This review resulted in a software hardening release that addresses multiple internally discovered vulnerabilities.
The vulnerabilities tracked by CVE-2026-76456 are related to improper input validation of special elements used in a command issue that are grouped under the Common Weakness Enumeration (CWE) CWE-20.
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Analysis
by VulDB Data Team • 10/07/2026
Cisco has released a software hardening update for NX-OS following an internal security review aimed at addressing multiple internally discovered vulnerabilities. This proactive measure underscores the vendor's commitment to maintaining product quality and securing network infrastructure against emerging threats. The specific vulnerability tracked under CVE-2026-76456 stems from improper input validation of special elements used in command execution contexts within the NX-OS operating system. By classifying this flaw under CWE-20, which denotes Improper Input Validation, Cisco highlights a fundamental failure to adequately sanitize or verify user-supplied data before processing it through critical system commands.
The technical nature of this vulnerability involves insufficient checks on special characters and control sequences that can be embedded within command inputs. In network operating systems like NX-OS, the command-line interface serves as a primary vector for configuration changes and operational management. When input validation is lax, malicious actors or compromised scripts may inject unexpected commands or alter existing ones by exploiting how these special elements are parsed. This lack of rigorous filtering allows data that should be treated as literal text to instead be interpreted as executable logic, potentially leading to unintended command execution or state manipulation within the device's control plane.
The operational impact of this flaw is significant for organizations relying on Cisco NX-OS for their core network infrastructure. If exploited successfully, an attacker could leverage improper input validation to execute arbitrary commands with the privileges associated with the affected process. This capability can lead to a complete compromise of the network device, allowing unauthorized access to sensitive data, disruption of network services through denial-of-service conditions, or use of the compromised node as a pivot point for further attacks against internal systems. The severity is amplified by the fact that command injection vulnerabilities often require only authenticated user access with specific privilege levels, making them accessible to insiders or attackers who have gained foothold within the administrative perimeter.
To mitigate this risk, administrators must apply the provided software hardening release immediately upon availability. This update contains the necessary patches to enforce stricter input validation rules and sanitize special elements during command processing. Beyond patching, organizations should implement defense-in-depth strategies such as restricting CLI access through role-based access control, enabling comprehensive logging of all administrative actions, and monitoring for anomalous command patterns that may indicate exploitation attempts. Aligning with ATT&CK techniques related to Command and Scripting Interpreter abuse can help security teams detect potential misuse of these interfaces before significant damage occurs. Regular audits of configuration changes and continuous vulnerability management practices are essential to maintaining the integrity of network operations against such input validation flaws.