Netis AC1200 Router NC21 V4.0.1.4296 stores a hard‑coded root password in /etc/shadow.sample. The password is simply 'root', giving anyone who can access the device the ability to authenticate as the system superuser. This gives the attacker full control of the underlying operating system, enabling any malicious action that requires root privileges.

Vendors: Netis; Product: AC1200 Router NC21; Firmware version V4.0.1.4296. The affected component is the router's authentication subsystem and the shadow sample file. No other versions are listed as affected.

With the trivial credential in place, an attacker who can reach the device—whether via local physical connection, compromised LAN, or remote management interface—can easily log in as root. The vulnerability has a CVSS score of 7.3, indicating high severity, and is an authentication flaw (CWE-798). No public exploit or proof‑of‑concept is documented, and it does not appear in CISA KEV. The EPSS score is < 1%, and the lack of updates makes this a pressing risk for routers still running the vulnerable firmware.