SQL injection vulnerability in calendar/event.php in the calendar implementation in Moodle 1.9.x before 1.9.18 allows remote authenticated users to execute arbitrary SQL commands via a crafted calendar event.
The product constructs all or part of an SQL command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended SQL command when it is sent to a downstream component. Without sufficient removal or quoting of SQL syntax in user-controllable inputs, the generated SQL query can cause those inputs to be interpreted as SQL instead of ordinary user data.