Listings showing nodes but not JOINing the node table show all nodes regardless of restrictions imposed by the node_access system. In core, this affects the taxonomy and the forum subsystem.
This issue only affects sites using a node access module such as content access or forum access. If you do not use any node access system then your site is not affected by this vulnerability. It is still considered a best practice to run the latest release and all site owners are encouraged to upgrade when they can regardless of whether or not they are affected.
Note that fixing this issue in contributed modules requires a backwards-compatible API change for modules listing nodes. See <http://drupal.org/node/1204572> for more details.
This issue affects Drupal 7.x only.
Install the latest version:
The Security Team has released both a pure security update without other bug fixes and a security update combined with other bug fixes and improvements. You can choose to either only include the security update for an immediate fix (which might require less quality assurance and testing) or more fixes and improvements alongside the security fixes by choosing between Drupal 7.3 and Drupal 7.4. Read the announcement for more information.
See also the Drupal core project page.