How hard is it to just boot an older kernel and rollback the default? Before I even thought about patching sensitive systems tonight the first thing our IT director asked was if I had a rollback plan. The answer? "Yes, boot old kernel, yum history undo [transaction id], reboot".

Always have a backout plan when doing upgrades, I'm just glad EL and derived distributions have an easy way to do it with yum's transaction history.