What is Session Fixation?
Session Fixaton also, known as "Session Fixation Attack" actualy is a kind of security risk on web application. If a web application don't change your Session ID after you login, there is a Session Fixation vulnerability on the application.
Testing for Session Fixation is very easy. You can use Burpsuite or simply Developer Tools (F12) of your browser.
** DISCLAIMER **
This video produced for only educational purpose.