Assuming you have the yum security plugin installed, to list available security updates use:
Code:
yum --security check-update
To update only security issues, use, as root:
Code:
yum --security update
To check if the yum security plugin is installed:
Code:
yum list installed yum-plugin-security
... or ...
Code:
rpm -q yum-plugin-security
To install the yum security plugin (if it is not installed), as root:
Code:
yum install yum-plugin-security
And to read more about yum security related commands (with the plugin installed):