The security issue in one sentence: SlickStack gives root a recurring job to download and install shell scripts from the operator's personal domain (slick.fyi), then run them from /var/www/crons/.

The updater "heals" cron files on a schedule by wget'ing text from slick.fyi, checking for a marker string, moving the result into place, chmod 0700, chown root:root, and leaving root's crontab to execute it — including minutely/hourly update hooks. There is no package signature, no reproducible build, and no separate approval step; you are trusting whoever controls that hostname with UID 0 on a timer.

If slick.fyi is compromised, DNS is poisoned, or TLS is intercepted, you do not get a failed apt upgrade; you get arbitrary code as root on every SlickStack box, automatically. That is not defense in depth; it is a built-in privileged remote-code channel marketed as convenience.