A missing authorization check in the AiController::openAnswerGrade method allows any authenticated user to retrieve the AI‑generated grading of another student’s exam attempts. The flaw enables the attacker to enumerate execution identifiers and question identifiers sent to the open_answer_grade endpoint, obtain feedback containing the other student’s answers, and consume the platform’s AI quota. This results in privacy violations and potential academic integrity compromises for impacted learners. The weakness is a CWE-639 authorization bypass.

Chamilo Learning Management System versions from 2.0.0-alpha.4 up to and including 2.0.0-RC.2 are affected. Updating to a release that is 2.0.0-RC.3 or later resolves the issue; older releases without the patch remain vulnerable.

The CVSS score of 5.3 indicates moderate severity. The EPSS score is not reported, and the vulnerability is not listed in the CISA KEV catalog, suggesting limited public exploitation data. The attack requires a valid authenticated session; the likely vector involves sending crafted requests to the open_answer_grade endpoint from a student or staff account. Once authenticated, the attacker can systematically enumerate parameters to access other students’ responses and exhaust AI resources.