SilverStripe 3.1.14 is now available, and all users of 3.1.13 or below are advised to upgrade at your convenience.
This release contains some low severity security issues, as well as a number of other bugfixes.
Details of these security fixes (ss-2015-015, ss-2015-016 and ss-2015-020) can be read on the security releases page.
To get setup, you can install this using composer (as below):
composer create-project silverstripe/installer path/to/project 3.1.14
Release notes: https://docs.silverstripe.org/en/3.1/changelogs/3.1.14/