VULNERABILITY DETAILS - CSRF in gmail
CSRF vulnerability in mail.google.com. 
1. CSRF token must be reset after gmail login. CSRF token remains same even after login and logout. 
2. CSRF token remains same for both get and post request. It is insecure to pass CSRF token in get request, it is advised to allow CSRF token in get request if and only if we reset on every request.
3. When multiple users login in the same browser, CSRF token remains same irrespective of user.

VERSION
Chrome Version: Any
Operating System: Any

REPRODUCTION CASE
I think description given in the vulnerability is enough, if needed i will demonstrate it.