CGI has the -utf8 pragma:

This makes CGI.pm treat all parameters as UTF-8 strings. Use this with care, as it will interfere with the processing of binary uploads. It is better to manually select which fields are expected to return utf-8 strings and convert them using code like this:

     use Encode;
     my $arg = decode utf8=>param('foo');
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The problem with binary (file) uploads is due to CGI's legacy, as it partially treats file uploads as form parameters instead of keeping both separate.

Alexander