Updating firmware on a HP Color LaserJet CP2025dn
Solution 1:
Sometimes a firmware upgrade can also be done from a virtual machine running Windows but I have no experience if this works in your case. If you do so, then there is a great risk for spoiling your hardware EPROM (e.g. if the virtual machine or the USB connection crashes at some point during the upgrade process).
I recommend the far easiest and safest way: plug in any PC/Laptop running Windows2000 or later, upgrade from there and be happy.
Solution 2:
Well, here's how I managed to do it: I ran the Windows firmware update utility under Wine and it worked.
I don't recommend this solution as a lot of things could go very wrong by doing it, but it worked for me.
I wish HP would have a tool for Ubuntu users.