In Yeastar N412 and N824 Configuration Panel 42.x and 45.x, an unauthenticated attacker can create backup file and download it, revealing admin hash, allowing, once cracked, to login inside the Configuration Panel, otherwise, replacing the hash in the archive and restoring it on the device which will change admin password granting access to the device.
https://www.yeastar.com/n-series-analog-phone-system/
https://www.swascan.com/security-advisory-yeastar-n412-and-n824-configuration-panel/