Permissions, Privileges, and Access Controls
mod/forum/rsslib.php in Moodle 2.1.x before 2.1.7 and 2.2.x before 2.2.4 does not properly implement the requirement for posting before reading a Q&A forum, which allows remote authenticated users to bypass intended access restrictions by leveraging the student role and reading the RSS feed for a forum.
CWE-264 - Permissions Privileges and Access Controls
CWE 264 (permissions, privileges, and access controls) is not a weakness in and of itself, rather it is a category of weaknesses related to the management of permissions, privileges, and other security features used to perform access control. If not addressed, the weaknesses in this category allow attackers to gain privileges for an unintended sphere of control, access sensitive information, and execute arbitrary commands.