You should really use <code> </code> tags around your code. It'll look a lot better, like this:

#!/usr/bin/perl

use strict;
use warnings;
use Data::Dumper;

my %hash1 = ( key1 => "val1",
              key2 => "val2",
              key3 => "val3",
              key4 => "val4",
              key5 => "val5");
my %hash2 = ( key1 => "xxxval1",
              key2 => "xxxval2");

print Dumper(%hash1), "\n";
out:foreach my $key (keys %hash1)
{
    foreach my $inkey (keys %hash2)
    {
        if($key eq $inkey)
        {
            $hash1{$key} = $hash2{$inkey};
            next out;
        }
    }
}

print Dumper %hash1;

__END__
[download]

However, I put it to you that the nested foreach loops are unnecessary, and that this does the same thing:

#!/usr/bin/perl

use strict;
use warnings;
use Data::Dumper;

my %hash1 = ( key1 => "val1",
              key2 => "val2",
              key3 => "val3",
              key4 => "val4",
              key5 => "val5");
my %hash2 = ( key1 => "xxxval1",
              key2 => "xxxval2");

print Dumper(%hash1), "\n";

foreach my $inkey (keys %hash2)
{
    if(exists $hash1{$inkey})
    {
        $hash1{$inkey} = $hash2{$inkey};
    }
}

print Dumper %hash1;

__END__
[download]

Because hey! It's a hash! There's no need to loop over the keys to see what's in it.