The Drupal Project reports:
In some circumstances Drupal allows user-supplied data to become part of response headers. As this user-supplied data is not always properly escaped, this can be exploited by malicious users to execute HTTP response splitting attacks which may lead to a variety of issues, among them cache poisoning, cross-user defacement and injection of arbitrary code.
The Drupal installer allows any visitor to provide credentials for a database when the site's own database is not reachable. This allows attackers to run arbitrary code on the site's server. An immediate workaround is the removal of the file install.php in the Drupal root directory.
The Drupal Forms API protects against cross site request forgeries (CSRF), where a malicious site can cause a user to unintentionally submit a form to a site where he is authenticated. The user deletion form does not follow the standard Forms API submission model and is therefore not protected against this type of attack. A CSRF attack may result in the deletion of users.
The publication status of comments is not passed during the hook_comments API operation, causing various modules that rely on the publication status (such as Organic groups, or Subscriptions) to mail out unpublished comments.