Is it possible to read 3rd party cookies

No, it's impossible.

You can only read cookies that come from your own domain. The other cookies are not even sent to your server.

If you could read every cookies the user has, you would be able to obtain personal information such as their facebook password, connection to their bank etc.

It would be a serious breach of privacy, and as such, browsers do not send cookies except those from the same domain.

No

When you visit a website, your web browser requests information from that domain (somedomain.com), and that third-party domain is allowed to set a cookie. Each domain can only read the cookie it created, so there is no way anotherdomain.com could access the cookie created by somedomain.com.