Analysis Summary

A critical vulnerability CVE-2025-20163 affecting Cisco Nexus Dashboard Fabric Controller (NDFC), formerly known as Data Center Network Manager (DCNM) in versions 11.5 and earlier, has been identified under Cisco Bug ID CSCwm50501. This flaw stems from improper SSH host key validation during connection establishment, aligning with CWE-322 (Key Exchange Without Entity Authentication). This implementation weakness enables Machine-in-the-Middle (MITM) attacks, where malicious actors can intercept or manipulate traffic between the NDFC controller and managed network devices by exploiting the lack of entity authentication during SSH communication.

The vulnerability is technically classified as a CVSS score of (High). This rating highlights that while the attack requires high complexity, it does not demand user interaction or authentication, and it can be executed remotely. Affected systems include all NDFC versions prior to 12.2.3, including legacy DCNM versions. Exploitation requires only network-level access to SSH traffic (TCP port 22) between the controller and devices, making environments with exposed management interfaces particularly vulnerable.

Successful exploitation can lead to device impersonation, enabling attackers to intercept sensitive credentials, alter configuration data, and potentially inject malicious commands into network operations. These fraudulent SSH sessions appear legitimate to administrators, increasing the risk of persistent backdoors and broader compromise of network infrastructure. The severity is amplified by the centralized role of NDFC in managing data center networks, making this an attractive target for sophisticated threat actors aiming for lateral movement and long-term access.

Cisco has addressed the issue in NDFC Release 12.2.3, bundled with Cisco Nexus Dashboard Release 3.2(2f), which includes enhanced SSH host key verification mechanisms. Notably, this new feature is disabled by default to ensure backward compatibility, although Cisco plans to enable it by default in future releases. There are no workarounds for affected versions, and customers using Nexus Dashboard Release 3.1 must upgrade immediately, as no patch is available. Administrators are advised to review the SSH Host Key Mismatch section in the official setup documentation for proper deployment and configuration. Organizations should prioritize this update to mitigate the risk of credential theft and unauthorized access.

Impact

• Sensitive Credentials Theft
• Gain Access

Indicators of Compromise

CVE

• CVE-2025-20163

Affected Vendors

Remediation

• Refer to the Cisco Security Advisory for patch, upgrade, or suggested workaround information.
• Included in Cisco Nexus Dashboard Release 3.2(2f), this version contains the security fixes addressing the SSH vulnerability.
• No patch is available for Release 3.1, so affected systems must be upgraded to a fixed version.
• Introduced in Release 12.2.3 to enhance SSH security and prevent device impersonation: This feature is disabled by default to maintain compatibility, and Cisco plans to enable it by default in future releases.
• Administrators should refer to the "SSH Host Key Mismatch" section in the Cisco NDFC Overview and Initial Setup documentation for correct configuration.
• Due to the high CVSS score (8.7) and potential for credential compromise, organizations should treat this upgrade as a security-critical task.