The My Home implementation in the block_html_pluginfile function in blocks/html/lib.php in Moodle through 2.3.11, 2.4.x before 2.4.10, 2.5.x before 2.5.6, and 2.6.x before 2.6.3 does not properly restrict file access, which allows remote attackers to obtain sensitive information by visiting an HTML block.