Directory traversal vulnerability in the min_get_slash_argument function in lib/configonlylib.php in Moodle through 2.5.9, 2.6.x before 2.6.8, 2.7.x before 2.7.5, and 2.8.x before 2.8.3 allows remote authenticated users to read arbitrary files via a .. (dot dot) in the file parameter, as demonstrated by reading PHP scripts.