Permissions, Privileges, and Access Controls
The moodle_enrol_external:role_assign function in enrol/externallib.php in Moodle 2.0.x before 2.0.4 and 2.1.x before 2.1.1 does not have an authorization check, which allows remote authenticated users to gain privileges by making a role assignment.
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.