cmp compares strings. You should use <=> instead.

Your code will only print one record if two have the same number, because the hash key $sorted[0] is not unique. The second (and third, etc) time you set a given hash element, the previously set value is lost. What follows is the same program, but it uses an array to avoid erasing records with the same number.

use strict;
use warnings;

print "Content-type: text/html\n\n";

my @records;
while (<DATA>) {
    chomp;
    push(@records, [ split(/\|/) ]);
}

print "$_->[0]|$_->[1]|$_->[2]<BR>\n"
   foreach sort { $b->[0] <=> $a->[0] } @records;
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