Can ColdFusion 11 process .htm and .html extensions?
Files with .htm and .html extensions are *normally* handled by the web server. ColdFusion doesn't touch them.
Do you have a special circumstance where you need CF to process HTML pages?
ColdFusion can process any file extension if you configure the web server to pass those files through to CF. What web server are you using? As a side note, i you are just trying to hide the fact that you are using ColdFusion for security reasons, rewrite rules on your web server might be a better option.