Is it possible to share session between different PHP versions?

Question

I am starting an old app refactoring, I will rebuild some functionality from spaghetti code to MVC (Symfony). Plan was I will set up new IIS app, using subdomain. Now, old app is running PHP 5.3 which can't be upgraded. New app will be running on PHP 5.6. Only thing I need to carry is authentication. I can have login script either on old or new app. I tried setting session cookie params but I can't get it working.

Is it possible at all or do I have to use database? If it is not possible, can that be achieved in Apache?

Edit:

What I'm to do is:

session.cookie_domain = ".dev" 

In both php.ini. Then I start the session in one, set a session variable.

session_start();
$_SESSION['test'] = 123;

Then in the second app (php 5.6) I'm trying to read it:

session_start();
var_dump($_SESSION);

But it's empty.

Answer 1

Apparently setting session cookie domains does not work for top level domains (TLD), like .dev

Changed my code to:

ini_set('session.cookie_domain', '.local.dev');

and now I am able to set session variables on .local.dev website and read them in new.local.dev

Both apps are physically in separate folders, operate from two IIS entries and using different PHP versions.