Originally posted by revolution
if you are using an rpm install of plesk on redhat or fedora, for example, you can upgrade apache, php and mysql from the official redhat/fedora update sites without any problem. they have nothing to do with plesk's interface.
on redhat:
up2date -u php apache mysql
on fedora:
yum update php apache mysql
keep in mind that you can't upgrade to any version you want. stick to offical updates from your distro and you should be fine.
by the way, if someone wants to tighten down security for a server's plesk interface because they are concerned with apache exploits there, one option is to use iptables to block access to port 8443 for anyone except authorized IPs. or, even better, just setup a special hostname on that server that you only tell your clients and domain owners about and use mod_rewrite and mod_proxy to proxy through requests there to plesk locally, and block direct access to 8443 from outside.