Hardcoded Cryptographic Key in Tenda NVR_4H CH3

Executive Summary

CVE-2026-79551 involves a hardcoded cryptographic key in Tenda Technology's NVR_4H network video recorder (CH3V2.1) running firmware V27.5.58.6. The device contains identical ECDSA private keys and self-signed certificates across all units, embedded during firmware build. Attackers on the same network can exploit this by decrypting HTTPS traffic to steal credentials and modify device communication.

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Detection Guidance

Check if your Tenda NVR_4H device is running firmware version V27.5.58.6 by logging into the admin interface or checking the device settings. Verify the presence of hardcoded files /etc/privkey.pem and /etc/cacert.pem on the device filesystem, which indicate the vulnerability. Use network monitoring tools like Wireshark to inspect HTTPS traffic for decryption using the known hardcoded private key.

Commands to detect: 1) SSH into the device and run 'cat /etc/privkey.pem' or 'cat /etc/cacert.pem'. 2) Use 'uname -a' to check firmware version. 3) Monitor network traffic for ARP spoofing or DNS poisoning attempts targeting the device.

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Impact Analysis

An attacker could intercept and decrypt sensitive data like admin login credentials, session tokens, camera RTSP credentials, and device configurations. They can also modify device communication without triggering browser warnings. The impact includes unauthorized access to the device, potential surveillance footage exposure, and manipulation of device settings.

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Compliance Impact

This vulnerability likely violates data protection requirements under GDPR and HIPAA by exposing sensitive video surveillance data and user credentials. Organizations using affected devices may face compliance violations due to inadequate protection of personal data and insufficient cryptographic controls.

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Mitigation Strategies

Immediately isolate the affected Tenda NVR_4H device from your network to prevent potential exploitation. Contact Tenda support to request a patched firmware version that removes hardcoded keys. If no patch is available, consider replacing the device with a model that supports unique per-device cryptographic keys.

Temporarily disable remote access to the device via HTTPS if possible. Monitor network traffic for suspicious activity and change all credentials (admin, camera RTSP, etc.) that may have been exposed. Ensure no sensitive data was transmitted over the vulnerable connection.

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