The new updates, which are also offered as optional via Windows Update so that as a manual download in the Microsoft Update Catalog, come with rather small changelogs, bringing just one and two changes, respectively.
To begin with, it's the Windows 7 monthly rollup preview which is labeled KB4516048.
This update includes just one fix that's aimed at software produced by Toshiba. According to the official changelog (which you'll find around the page linked above):
"Addresses an issue that may cause an error when opening or while using Toshiba Qosmio AV Center. You may also get an error in case Log associated with cryptnet.dll."
Windows 8.1 improvements
Second of all, Windows 8.1 devices are provided with monthly rollup preview KB4516041.
This time around, there's two changes, one of these concerns an insect hitting Ie. According to Microsoft, Internet Explorer 11 didn't launch on Windows 8.1 RT devices after installing update KB4516067, so this rollup is supposed to fix the error and restore the standard behavior on devices running this OS. However, given it's aimed at RT systems, there's an opportunity the amount of users influenced by this glitch is incredibly low.
And 2nd, the same update fixes a problem striking the LSASS service, as Microsoft explains:
"Addresses an element that may cause the neighborhood Security Authority Subsystem Service (LSASS) to prevent working with an "0xc0000005" error."
The improvements during these monthly rollup previews is going to be area of the stable updates shipped to users on October 8 included in the next Patch Tuesday cycle. At that time, the updates will be offered automatically through Windows Update.