The team of developers working on Moodle have recently released Moodle 2.0.3 and Moodle 1.9.12. In addition to a number of bug fixes and small improvements, five security vulnerabilities (4 major, 1 minor) in 2.0.2 and two security vulnerabilities (both major) in 1.9.11 have been discovered and fixed.
As always, they recommend that you upgrade your sites to these latest versions as soon as possible. All 50,000 admins of registered Moodle sites have been notified previously.
Upgrading from 2.0.x or 1.9.x should be very straightforward. Full details about the releases can be found in the Moodle 2.0.3 release notes and the Moodle 1.9.12 release notes.
The releases themselves are available from the Moodle download page or CVS/Git.
The Moodle development team is working hard on Moodle 2.1, with a release date planned for 30th June 2011.