Recently, Nokia has been in touch with some CSSU devs and the council about a possible software update.
As the version number implies, this is just a simple fix for the DigiNotar issue.
As of version 16.8, the CSSU includes these security fixes, you should not try to update your device (the update will not show up in Application Manager).
The latest Nokia update will also include a fixed security control panel applet, this will be pulled into the CSSU right after it's released publicly so the CSSU can be right back on track.
The update should be out in a couple of days for everyone, again, please do not try to update if you're using the CSSU (using apt-get or similar methods).
Non-CSSU users, you can update. If you ever want to install the CSSU, the installer will work fine on PR1.3.1.