Drupal 7.11 and 6.23, maintenance releases which fix security vulnerabilities are now available for download.
Drupal 7.12 and 6.24 also fix other issues reported through the bug tracking system.
Upgrading your existing Drupal 7 and 6 sites is strongly recommended. There are no new features in these releases. For more information about the Drupal 7.x release series, consult the Drupal 7.0 release announcement, more information on the 6.x releases can be found in the Drupal 6.0 release announcement. Drupal 5 is no longer maintained, upgrading to Drupal 6 is recommended.
Drupal 7.11 only includes fixes for security issues. Drupal 7.12 also includes bugfixes. The full list of changes between the 7.10 and 7.12 releases can be found by reading the 7.12 release notes. A complete list of all bug fixes in the stable 7.x branch can be found in the git commit log.
Drupal 6.23 only includes fixes for security issues. Drupal 6.24 also includes bugfixes. The full list of changes between the 6.22 and 6.24 releases can be found by reading the 6.24 release notes. A complete list of all bug fixes in the stable 6.x branch can be found at git commit log.
Drupal 7.11 and 6.23 were released in response to the discovery of security vulnerabilities. Details can be found in the official security advisory:
To fix the security problem, please upgrade Drupal.
The default.settings.php file was changed in Drupal 7.12, to add documentation about PDO attribute override capabilities that were added as a result of #1309278: Make PDO connection options configurable.
The robots.txt file was changed in Drupal 6.24 to block filter tips from search engines. The .htaccess and (default.)settings.php files were not changed in Drupal 6. Additionally, indexes were added to the node_comment_statistics and comment tables, for performance.
Bug fixes in 7.12 release cause problems with the Internationalization (i18n) module, and there are reports of the same about Menu Block: #1425342: Drupal core upgrade from 7.10 to 7.12 causes menu block to fail. Users of these modules are encouraged to update to 7.11 to get the security fixes, and hold off on the 7.12 upgrade until #1351678: Follow menu_link_get_preferred active trail handling for custom menus and #1050466: The taxonomy index should be maintained in a node hook, not a field hook are resolved. (Note: Help here would be greatly appreciated!)
In Drupal 6.24, if you have the contributed user_delete module enabled on your site, the update will fail with a Cannot redeclare user_delete_access() error. An update of user_delete module is being worked on.
In Drupal 6.24 if you had locale module enabled earlier, but it is not currently turned on, the update will fail with Call to undefined function locale_inc_callback(). A fix is being worked on for Drupal core.