We invest heavily in quality control at Autodesk, but when issues arise, product updates and fixes ensure the continued success of our customers. Transparency is important to us, which is why we want to share that we provided an update (AutoCAD 2018.0.1) very shortly after the AutoCAD 2018 launch to fix a bug in the product. We discovered a mistake we made with this update, quickly removed it to resolve the issue, and then provided a subsequent update (AutoCAD 2018.0.2) to resolve the root problem as soon as possible. More information is available via AutoCAD forums.
As a quick reminder, the Autodesk Desktop App introduced last year is an AutoCAD companion application that delivers security patches and updates for all versions of Microsoft Windows-based Autodesk products from 2015 on, as well as relevant learning content. More information about how it works is available here.
I have ACAD 2017, and I haven't done any upgrade, do I need to do the upgrade?
No. The this particular update only applies to AutoCAD 2018.