Update: Drupal 7.21 is now available.
Drupal 7.20, a maintenance release which contains fixes for security vulnerabilities, is now available for download. See the Drupal 7.20 release notes for further information.
Upgrading your existing Drupal 7 sites is strongly recommended. There are no new features or non-security-related bug fixes in this release. For more information about the Drupal 7.x release series, consult the Drupal 7.0 release announcement.
Drupal 7.20 is a security release only. For more details, see the 7.20 release notes.
A complete list of all bug fixes in the stable 7.x branch can be found in the git commit log.
Drupal 7.20 was released in response to the discovery of security vulnerabilities. Details can be found in the official security advisory:
To fix the security problems, please upgrade to Drupal 7.20.
Due to the nature of the security fix, some sites will require extra testing and care when deploying this release of Drupal core, and several contributed modules require code changes in order to continue working correctly. See the release notes for more information.