ColdFusion V 8

Well, there are two ways to answer this.

The first is that you may well find that you can update the OS and it will have NO EFFECT on your existing running CF. Instead, the problem most folks encounter when they have such an old CF version is that its INSTALLER will no longer work on the later OS, or the CF web server config tool will no longer work.  But if you are really just upgrading the server's OS, you may be "ok"...at least until you have to ever run the wsconfig tool (perhaps you never do).

The second is to beware that CF8 is VERY old, and has not been updated since 2012. You are at grave security risk in running anything that old, or CF9, or even 10 or 11, as those are no longer updated either. Such updates fix important security vulnerabilities, and even for an "internal server" that "no one can reach from the outside", you are just asking for trouble (and even could be legally liable for damages) in running such an old version.