What vulnerability can be when CSRF token is equivalent to session id?

Question

CSRF

Those. I understand that it is necessary that the csrf token be unique and stored in the session.
But I'm working with a legacy project and there CSRF token is the session id
. With each request to the server, the token is added to the request and taken from the cookies like this
req.token =Ext.util.Cookies.get(Main.session_name);
After that, the server is simply checked like this:
$_POST['token'] ==$_COOKIE[$cookie_name] and if they are equal, then we work with the form data
(cookie: sid: 1234567890
req{token: 1234567890})
But I I can’t imagine how such an implementation can be exploited
If we force the user to go to our script that makes a request to the attacked server
then the browser will automatically send a request with the session () taken from the browser, but you can’t force it to send the same sessionid post from the cookies?