The Twitter module 6.x-5.x before 6.x-5.2, 7.x-5.x before 7.x-5.9, and 7.x-6.x before 7.x-6.0 for Drupal does not properly check access permissions, which allows remote authenticated users to post tweets to arbitrary accounts by leveraging the (1) "post to twitter" permission or change the options for arbitrary attached accounts by leveraging the (2) "add twitter accounts" or (3) "add authenticated twitter accounts" permission.