Chamilo LMS is an open-source learning management system. Prior to 1.11.40 and 2.0.1, an authenticated administrator can call the get_sessions action in /main/inc/ajax/model.ajax.php with _search=true and a crafted JSON filters parameter whose groupOp field contains SQL syntax. Because groupOp is not restricted to the expected AND or OR operators before it is incorporated into query logic, attacker-controlled input is interpreted by the database and enables blind or time-based SQL injection. Successful exploitation can disclose sensitive user, course, session, configuration, password-reset, and administrative data, modify or delete records subject to database privileges, and cause denial of service through expensive delayed queries. This issue is fixed in versions 1.11.40 and 2.0.1.