Attack Chain

1. Attacker authenticates to the target Nginx-UI instance and obtains a valid JWT.
2. Attacker initiates an authorized backup request to GET /api/backup to retrieve current encrypted backup artifacts and the required X-Backup-Security token.
3. Attacker decrypts the retrieved backup archive using the extracted security token and IV.
4. Attacker modifies the app.ini file within the decrypted archive to include a malicious payload in the TestConfigCmd setting.
5. Attacker re-encrypts the modified backup archive and regenerates the manifest signature using the same HMAC key derivation logic.
6. Attacker uploads the forged backup via POST /api/restore with the malicious payload included.
7. Attacker invokes POST /api/nginx/test to force the application to execute the modified TestConfigCmd.
8. Arbitrary code executes within the Nginx-UI container context, completing the exploit chain.

Impact

Successful exploitation results in full command execution within the Nginx-UI runtime environment. An attacker can use this access to read or modify sensitive configuration data, extract JWT secrets, corrupt application state, or move laterally within the host environment, depending on the container's privileges and host integration.

Recommendation

Prioritized actions for detection and mitigation:

• Patch Nginx-UI to version 1.9.10-0.20260728074146-a467ed652591 or later to remediate CVE-2026-107806.
• Deploy WAF or web server rules to audit or block POST requests to /api/restore and /api/nginx/test originating from non-administrative user accounts.
• Monitor logs for unusual configuration changes, specifically modifications to app.ini or attempts to trigger nginx test command execution from suspicious user sessions.
• Restrict access to the Nginx-UI interface to trusted internal networks only to minimize the exposure of administrative endpoints.