If the filename contains metacharacters this may lead to undesired behavior:

open(LOCAL, ">/var/www/html/pmuze/upload/$username/$fileName")
[download]

I would highly recommend to use a three argument call to open as to avoid the open function from performing any magic.

Excerpt from open function Perl documenattion:

The filename passed to 2-argument (or 1-argument) form of open() will have leading and trailing whitespace deleted, and the normal redirection characters honored. This property, known as "magic open", can often be used to good effect. A user could specify a filename of "rsh cat file |", or you could change certain filenames as needed.
Use 3-argument form to open a file with arbitrary weird characters in it.

In particular for filenames received via webforms you want to be careful.