To run the latest 4.2 version on Fedora or RedHat/CentOS you can use the instructions from here. To install and enable VirtualBox guest additions on your Fedora Linux, you must have VirtualBox installed on your system, if not install it using our guide: How to Install VirtualBox in Fedora Linux. With this latest update Fedora Rawhide (as of today running Xorg-1.14 and kernel 3.9.2.1.fc20.x86_64) is now fully supported as seen in the screenshot below. This is guide, howto install Oracle VirtualBox Guest Additions on Fedora 34/33/32, CentOS 8/7/6 and Red Hat (RHEL) 8/7/6.Fedora 34/33/32 kernels have build i. guest additions compile fix for Debian Linux kernel 3.2.0-4.guest additions compile fix for RHEL/OL/CentOS 6.4 guests (another annoying bug with a simple fix).fall-back to vesa driver on RedHat-based guests if vboxvideo fails to load (this was a really annoying bug since the alternative was to switch to a TTY to kill the failed X session and that was not always working).guest additions compile fix for kernel 3.8 and 3.9.Apart from the usual bug fixes there are a few that are worth mentioning:

Both of them include updates to improve stability and fix regressions. Oracle released updated versions for two of the current Virtual Box branches 4.1 and 4.2.

Fedora 26 virtualbox guest additions