Cross-site scripting (XSS) vulnerability in course/lib.php in Moodle 1.6 before 1.6.9, 1.7 before 1.7.7, 1.8 before 1.8.8, and 1.9 before 1.9.4 allows remote attackers to inject arbitrary web script or HTML via crafted log table information that is not properly handled when it is displayed in a log report.