If you are using a tunnel to browse the site and you are using a different port that what the service actually runs on, this can happen.
Th site checks that the IP and port matches what was requested.
Example:
The site runs on port 443 ( HTTPS ) and you have setup a tunnel to access the service locally on port 12345. You use your local browser to connect to https://127.0.0.1:12345 and the page loads.
The once you try and access some services, the page fails to load with an Error 403:
CSRF verification failed
The service is checking that the access was supposed to go to port 443, but sees port 12345.
Solution
Change the tunnel to a Dynamic Socks proxy and use that in your browser
or
change the port locally to the same port that the service is actually running on. ( E.g. 443 from the example above. )