One way is a recursive function:

sub trav_hash { 
    my $ref = shift;

    my $type = ref $ref;
    if( $type eq 'HASH' ) { 
        trav_hash( $ref->{$_} ) for keys %$ref;
    } elsif ( $type eq 'ARRAY' ) { 
        handle_array( $ref );
    } else { 
        die "something weird is in our structure!";
    }
}

sub handle_array { 
    my $arrayref = shift;

    # do whatever we want with the array here....
}

trav_hash( \%data );
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