Setting SMS media allows to set GSM modem file. Later this file is used as Linux device. But due everything is a file for Linux, it is possible to set another file, e.g. log file and zabbix_server will try to communicate with it as modem. As a result, log file will be broken with AT commands and small part for log file content will be leaked to UI.
https://support.zabbix.com/browse/ZBX-25013
https://lists.debian.org/debian-lts-announce/2024/10/msg00000.html