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 allowed extension list of the core Upload module contains
the extension HTML by default. Such files can be used to execute
arbitrary script code in the context of the affected site when a
user views the file. Revoking upload permissions or removing the
.html extension from the allowed extension list will stop uploads
of malicious files. but will do nothing to protect your site
againstfiles that are already present. Carefully inspect the file
system path for any HTML files. We recommend you remove any HTML
file you did not update yourself. You should look for , CSS
includes, Javascript includes, and onerror="" attributes if
you need to review files individually.
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to mail out unpublished comments.