The AT&T U-verse 9.2.2h0d83 firmware for the Arris NVG589 and NVG599 devices, when IP Passthrough mode is not used, configures ssh-permanent-enable WAN SSH logins to the remotessh account with the 5SaP9I26 password, which allows remote attackers to access a "Terminal shell v1.0" service, and subsequently obtain unrestricted root privileges, by establishing an SSH session and then entering certain shell metacharacters and BusyBox commands.
https://threatpost.com/bugs-in-arris-modems-distributed-by-att-vulnerable-to-trivial-attacks/127753/