rss/file.php in Moodle through 2.1.10, 2.2.x before 2.2.11, 2.3.x before 2.3.8, 2.4.x before 2.4.5, and 2.5.x before 2.5.1 does not properly implement the use of RSS tokens for impersonation, which allows remote authenticated users to obtain sensitive block information by reading an RSS feed.