Multiple cross-site request forgery (CSRF) vulnerabilities in user/messageselect.php in the messaging system in Moodle 2.2.x before 2.2.7, 2.3.x before 2.3.4, and 2.4.x before 2.4.1 allow remote attackers to hijack the authentication of arbitrary users for requests that send course messages.
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.