PHP Laravel Framework 5.5.40 / 5.6.x < 5.6.30 - token Unserialize Remote Command Execution

Unsure why you reported this here i.e. on a Laravel tutorial site?

Laravel has a very clear security policy - https://github.com/laravel/framework/security/policy

A two second Google also revealed https://github.com/laravel/framework/pull/25121/commits/d84cf988ed5d4661a4bf1fdcb08f5073835083a0

This issue has already been addressed. If you are using an up-to-date version of Laravel and you don't use cookie serialization, you should be in the clear. The vulnerability also needs the app key to be exploited.

https://laravel.com/docs/5.5/upgrade#upgrade-5.5.42