Moodle 2.0.x before 2.0.9, 2.1.x before 2.1.6, and 2.2.x before 2.2.3 allows remote authenticated users to bypass an activity's read-only state and modify the database by leveraging the student role and editing database activity entries that already exist.

Moodle 2.1.x before 2.1.6 and 2.2.x before 2.2.3 allows remote authenticated users to obtain sensitive user information from hidden fields by leveraging the teacher role and navigating to "Enrolled users" under the Users Settings section.

admin/roles/override.php in Moodle 2.0.x before 2.0.9, 2.1.x before 2.1.6, and 2.2.x before 2.2.3 allows remote authenticated users to gain privileges by leveraging the teacher role and modifying their own capabilities, as demonstrated by obtaining the backup:userinfo capability.

mod/data/preset.php in Moodle 2.1.x before 2.1.6 and 2.2.x before 2.2.3 does not properly iterate through an array, which allows remote authenticated users to overwrite arbitrary database activity presets via unspecified vectors.