my $outer = Text::CSV_XS->new ({ binary => 1, auto_diag => 1 });
my $inner = Text::CSV_XS->new ({ binary => 1, auto_diag => 1, sep_char => ":" });
my %hash;
while (my $row = $outer->getline ($fh)) {
    foreach (@$row) {
        $inner->parse ($_);
        my @f = $inner->fields;
        if (@f >= 2) { # assuming key:value:1 will result in $hash{key} = "value:1"
            my $key = shift @f;
            $hash{$key} = join ":" => @f;
            }
        else {
            warn "Probably not a key-value pair '$_'";
            }
        }
    }