Google has released the September 2018 security update, like clockwork, for its Nexus and Pixel smartphones. Those that are getting this month's update include the Nexus 5X and Nexus 6P, as well as the Pixel, Pixel XL, Pixel 2, Pixel 2 XL and Pixel C. Along with the security update, the Pixel 2 is also getting an update that will improve the consistency of WiFi connections with certain routers, which is going to be a good thing for those with the Pixel 2.
This security update for Nexus and Pixels fixes a slew of vulnerabilities, some of them are somewhat minor while others are more critical. Google does outline them to a degree in this month's security bulletin. Though Google does not go into depth about these vulnerabilities, as they can still be exploited on smartphones and tablets that have not yet received this month's security update. This is common practice for Google and its partners, in an effort to try to protect its users that haven't update yet. But this is also why it's important to update your phone or tablet when you do get an update to install. Instead of putting it off for days, weeks or even longer. As always, Google shared the code for this update with its partners about a month ago, so you should be seeing security updates coming for other smartphones coming in the next few days. Particularly those that are fast to update like BlackBerry and Samsung.
Those that have a Nexus or Pixel device, you should begin seeing the OTA arriving on your device in the next few days. Of course, you can always go to Settings, then About Phone and check for an update yourself. You also could flash the OTA on your device, but this update isn't that critical, so you can wait a few days for the update to arrive.