The weird character sequences are ansi escape sequences used to highlight or color the text on a *nix console. cmd.exe doesn't do ansi escape sequences so it displayes them literally.

Why CPAN.pm should be producing them I don't know. It didn't the last time I used it (a long while since). Maybe a new enhancement, and they got the test for OS wrong?

It could be 'fixed' by using Win32::Console::ANSI within cpan.pm itself. This converts the ANSI escape sequences into appropriate Console API calls effectively emulating a ANSI complient terminal. But I wouldn't advise a user to make that modification.

You need to work out why this happens for you, if nobody else is seeing the same problem?

The first thing you need to do is tell whomever is listening the details of your system: Which OS (exact version)? Which CPAN.pm (exact version)? Which Perl (exact version)? Perl source: AS, home build, other supplier? If home build, which compiler (and version(s))? Do you use cygwin? Was your perl built under cygwin?

Ie. a whole lot more than you have currently told us.

My guess is that you are using a cygwin built perl install, but trying to use it from a non-sygwin shell. And CPAN.pm has been built expecting a *nix-like environment and so is producing the escape sequences. But that's total speculation.