Risks
From MoodleDocs
Template:Moodle 1.7
This page describes the different types of risks that different capabilities can raise. (This page is incomplete and needs more information.)
Configuration
Users could change site configuration and behaviour
XSS (Cross-Site Scripting)
Users could add files and texts that allow cross-site scripting.
Privacy
Users could gain access to private information of other users
Spam
Users could send spam to site users or others