Algorithmic complexity vulnerability in the _filter_url function in the text filtering system (modules/filter/filter.module) in Drupal 7.x before 7.14 allows remote authenticated users with certain roles to cause a denial of service (CPU consumption) via a long email address.
Unspecified vulnerability in Drupal before 4.6.11, and 4.7 before 4.7.5, when MySQL is used, allows remote authenticated users to cause a denial of service by poisoning the page cache via unspecified vectors, which triggers erroneous 404 HTTP errors for pages that exist.