The SL 7.8 Live Media is now available.

It includes all updates from April 21 2020. The LiveCD has grown in
size to exceed traditional CD media.  However, it is much smaller than
the LiveDVDs.

The SL 7.8 Install Media was rebuilt to correct an error with the Dual-
Layer DVD image.  It is now the correct size for Dual Layer DVD media.

http://ftp.scientificlinux.org/linux/scientific/7/x86_64/iso/