A flaw was found in Moodle 3.4 to 3.4.1, and 3.3 to 3.3.4. If a user account using OAuth2 authentication method was once confirmed but later suspended, the user could still login to the site.
https://moodle.org/mod/forum/discuss.php?d=367939
http://www.securityfocus.com/bid/103725
http://git.moodle.org/gw?p=moodle.git&a=search&h=HEAD&st=commit&s=MDL-60101