Multiple cross-site request forgery (CSRF) vulnerabilities in the lesson module in Moodle through 2.6.11, 2.7.x before 2.7.11, 2.8.x before 2.8.9, and 2.9.x before 2.9.3 allow remote attackers to hijack the authentication of arbitrary users for requests to (1) mod/lesson/mediafile.php or (2) mod/lesson/view.php.
The web application does not, or cannot, sufficiently verify whether a request was intentionally provided by the user who sent the request, which could have originated from an unauthorized actor.