Incorrect permission assignment for critical resource issue exists in UD-LT1 firmware Ver.2.1.9 and earlier and UD-LT1/EX firmware Ver.2.1.9 and earlier. If an attacker with the guest account of the affected products accesses a specific file, the information containing credentials may be obtained.
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/