CVE-2025-20347: Cisco Nexus Dashboard Auth Bypass Vulnerability

CVE-2025-20347 Overview

Cisco disclosed CVE-2025-20347, a missing authorization vulnerability in the REST API endpoints of Cisco Nexus Dashboard and Cisco Nexus Dashboard Fabric Controller (NDFC). An authenticated, low-privileged, remote attacker can view sensitive configuration data or upload and modify files on an affected device. The flaw is tracked under CWE-693 (Protection Mechanism Failure). Cisco published the advisory on August 27, 2025.

Critical Impact
A low-privileged authenticated user can perform limited administrator functions, including reading HTTP proxy and NTP configuration, uploading images, and corrupting image files on the device.

Affected Products

Cisco Nexus Dashboard
Cisco Nexus Dashboard Fabric Controller (NDFC)
Deployments exposing REST API endpoints to authenticated low-privileged users

Discovery Timeline

2025-08-27 - Cisco publishes security advisory cisco-sa-nshs-urapi-gJuBVFpu
2025-08-27 - CVE-2025-20347 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-20347

Vulnerability Analysis

The vulnerability resides in several REST API endpoints of Cisco Nexus Dashboard and NDFC. These endpoints authenticate the caller but fail to verify whether the caller's role permits the requested action. As a result, a user holding only low-privileged credentials can invoke functions reserved for administrators.

Successful exploitation lets the attacker read sensitive infrastructure settings such as HTTP proxy and NTP configuration. The attacker can also upload new image files and damage existing ones, which affects the integrity of software artifacts staged on the controller. Confidentiality and integrity are impacted; availability of the platform itself is not directly affected according to the CVSS vector.

The issue is classified under CWE-693: Protection Mechanism Failure and requires network reachability to the management API.

Root Cause

The root cause is missing server-side authorization checks on specific REST API routes. The affected endpoints rely on authentication only and do not enforce role-based access control (RBAC) before executing privileged operations. This is a classic broken access control pattern in which the API implicitly trusts any authenticated session.

Attack Vector

Exploitation requires valid credentials for a low-privileged account on the Nexus Dashboard or NDFC instance. The attacker sends crafted HTTPS requests to the vulnerable API endpoints from any network location that can reach the management interface. No user interaction is required, and attack complexity is low.

See the Cisco Security Advisory for the authoritative list of affected endpoints and fixed releases.

Detection Methods for CVE-2025-20347

Indicators of Compromise

REST API calls to administrator-scoped endpoints originating from user accounts that do not hold the administrator role.
Unexpected image uploads or modifications to image repositories on Nexus Dashboard or NDFC.
Access to HTTP proxy or NTP configuration endpoints by non-administrator sessions.

Detection Strategies

Review Nexus Dashboard and NDFC audit logs for API requests where the authenticated principal's role does not match the sensitivity of the invoked endpoint.
Correlate authentication events with subsequent privileged API operations to identify horizontal or vertical privilege escalation attempts.
Alert on repeated 4xx or unusual 2xx responses on administrator API routes from low-privileged tokens.

Monitoring Recommendations

Forward Nexus Dashboard and NDFC API and audit logs to a centralized SIEM for retention and correlation.
Baseline normal administrator API usage and alert on deviations, especially file uploads and configuration reads.
Monitor management-plane network segments for unexpected HTTPS clients contacting the API.

How to Mitigate CVE-2025-20347

Immediate Actions Required

Apply the fixed software releases identified in the Cisco Security Advisory.
Audit local and remote accounts on Nexus Dashboard and NDFC and remove unused low-privileged accounts.
Rotate credentials for any account that may have been used against an unpatched instance.

Patch Information

Cisco has released fixed software for Nexus Dashboard and Nexus Dashboard Fabric Controller. Consult the vendor advisory cisco-sa-nshs-urapi-gJuBVFpu for the specific fixed versions that map to your deployment. No workaround is listed by Cisco, so upgrading is the primary remediation.

Workarounds

Restrict management network access to Nexus Dashboard and NDFC so that only trusted administrative hosts can reach the REST API.
Enforce strong authentication and least-privilege role assignment; avoid provisioning low-privileged accounts on production controllers where not required.
Integrate Nexus Dashboard with a centralized identity provider and enable multi-factor authentication (MFA) for all interactive accounts.

bash

# Example: restrict management API exposure with an upstream ACL
# Replace 10.10.0.0/24 with your administrator jump-host subnet
iptables -A INPUT -p tcp --dport 443 -s 10.10.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP