Zte F680 Exploit

Using a simple Python script, the attacker sends a POST request to /cgi-bin/telnet.cgi with no session cookie. If the device is vulnerable, the response 200 OK appears, and Telnet is enabled on port 23.

Alternatively, for devices behind NAT but with remote management (TR-069) exposed, attackers exploit the command injection on port 80.

Because the F680 is often an ISP-managed device, end-users have limited options for patching the firmware manually. However, the following mitigations are recommended:

The most severe and persistent exploit is not a bug—it’s a feature left over from development. zte f680 exploit

Discovery: Researchers found that many ZTE F680 units contain a secondary, undocumented user account.

Why it works: This password bypasses the web login lockout policies. It often grants access not just to the web UI, but to Telnet (Port 23) and SSH (Port 22) if those services are hidden in the GUI.

Impact: An attacker on your local network can simply attempt to Telnet to the router’s IP. If the firmware hasn’t been patched, they are instantly logged in as root—the highest privilege level. From there, they can: Using a simple Python script, the attacker sends

The most famous "exploit" for the F680 is not a bug but a deliberate backdoor. The device contains a hidden superuser account that cannot be deleted or changed via the standard web interface.

Credentials:

Why this works: The device checks for this specific string in the login POST request. If matched, it grants full administrative access (Telnet/SSH and Web GUI) without standard authentication checks. Why it works: This password bypasses the web

Impact:

From the compromised router, the attacker can:

While specific CVE numbers shift over time, the following vulnerability classes are consistently found across various firmware versions of the ZTE F680.

ZTE has released patches, but ISPs are slow to deploy them. You have two options: