SilverStripe 3.1.9 stable is now available, and all users of 3.1.8 or older are strongly advised to upgrade.
This update includes important security fixes. Details on these can be found at http://www.silverstripe.org/software/download/security-releases/
Release and upgrading notes can be found at http://beta.docs.silverstripe.org/en/changelogs/3.1.9/.
Download: http://www.silverstripe.org/software/download/.
Announcement: https://groups.google.com/forum/#!topic/silverstripe-announce/DfR-ZG3jcwM