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The vulnerability resides in the way Nginx-UI handles its master node secret mechanism, allowing it to be supplied via URL query parameters (?node_secret=). Because the application accepts this master credential in the query string, it gets persistently logged in plaintext across multiple operational surfaces including HTTP access logs, reverse proxy logs, browser history, and third-party HTTP Referer headers. Furthermore, the default cluster configuration format embeds these high-privilege secrets directly into configuration files (app.ini) and environment variables. An unauthorized actor or malicious insider who obtains read access to any of these log aggregators or deployment files can extract the master secret. This credential completely bypasses all standard JSON Web Tokens, session verifications, and two-factor authentication mechanisms for the entire application programming interface. Consequently, attackers achieve full, persistent, unauthenticated administrative control, enabling them to inspect TLS private keys, alter proxy routing configurations, and compromise downstream cluster nodes.
DailyCVE Form:
Platform: Nginx-UI
Version: All versions
Vulnerability : Auth Bypass
Severity: Critical
date: 2026-04-21
Prediction: 2026-05-10
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The core flaw originates from architectural oversights where security tokens are treated as query string parameters rather than strictly enforced header fields. By permitting credentials inside URLs, the application violates basic web security design principles, turning routine logging facilities into credential leakage vectors. Since the node secret acts as a master key mapping directly to an initial admin user context, any leakage vector compromises the entire application trust boundary instantly without requiring brute-force tactics.
Exploit: (Educational Purposes!)
To demonstrate log-based extraction of the node secret and subsequent API abuse, use the following bash commands:
Step 1: Extract node secrets from plaintext access logs grep -oP 'node_secret=[^&\s"]+' /var/log/nginx/access.log Step 2: Query the administrative settings endpoint using the leaked secret curl -s -H "X-Node-Secret: a1b2c3d4-e5f6-7890-abcd-ef1234567890" http://target:9000/api/settings Step 3: Read sensitive Nginx configurations using the node secret header curl -s -H "X-Node-Secret: a1b2c3d4-e5f6-7890-abcd-ef1234567890" "http://target:9000/api/nginx/config?filepath=/etc/nginx/nginx.conf"
Protection: from this CVE
To secure deployments against this vulnerability, apply the following code and configuration changes:
Remove query parameter fallback handling entirely from `getNodeSecret` and `isTrustedNodeRequest` functions to ensure credentials are exclusively parsed via the `X-Node-Secret` header.
Redesign cluster node configurations to separate sensitive tokens into restricted-permission key files rather than embedding them directly inside URL query strings.
Encrypt plaintext token values residing in the SQLite database columns using crypto settings secrets at rest.
Implement token rotation functionality within API endpoints to immediately invalidate legacy leaked credentials.
Impact
Complete confidentiality loss regarding TLS private keys, database contents, internal paths, and application configuration parameters.
Total integrity compromise allowing unauthorized generation, modification, or deletion of Nginx server configurations across clusters.
Availability risks via deliberate service disruptions, improper reloads, or malformed configurations causing denial of service conditions.
Persistent unauthorized access because node tokens lack automated expiration windows or native revocation features.
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Sources:
Reported By: github.com
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