The Forward module is a module that allows site administrators to add links to postings that let users email the current page to a third party. By manipulating URL arguments, authenticated and anonymous users are able to access posts that should have been restricted by a node access module such as Organic Groups, Taxonomy Access Control, Taxonomy Access Lite, etc.
Drupal core is not affected. If you do not use the contributed Forward module, there is nothing you need to do.
Install the latest version:
See also the Forward project page.
Drupal Security Team