Inclusion of undocumented features or chicken bits issue exists in UD-LT1 firmware Ver.2.1.8 and earlier and UD-LT1/EX firmware Ver.2.1.8 and earlier. A remote attacker may disable the firewall function of the affected products. As a result, an arbitrary OS command may be executed and/or configuration settings of the device may be altered.
https://www.securityweek.com/i-o-data-confirms-zero-day-attacks-on-routers-full-patches-pending/
https://www.iodata.jp/support/information/2024/11_ud-lt1/