while (<CONFIG>) 
{
    chomp;
    s/^\s+//;
    s/\s+$//;
    next unless length;
    my ($var, $value) = split(/\s*=\s*/, $_, 2);
    $cfg{$var} = $value;
}

var1=wert
var2=wert
var3=wert

my ($var, $value) = split(/\s*=\s*/, $_, 2);

C:\test>perl
use warnings; use strict;
$_ = "abc=def=geh\n";
chomp;
s/^s\+//; s/\s+$//;
my ($var, $value) = split(/\s*=\s*/, $_, 2);
print "\$var: $var\n";
print "\$value: $value\n";
^D
$var: abc
$value: def=geh