The Moodle OpenAI Chat Block plugin 3.0.1 (build 2025021700) suffers from an IDOR vulnerability due to insufficient validation of the blockId parameter in the completion.php API endpoint. This allows an authenticated student to impersonate another user's block, such as an administrator's, and send queries that execute with that block's configuration. The impact includes potential exposure of administrator-only Source of Truth entries, unauthorized modification of model behavior, and possible misuse of API resources. There is no indication of known exploits in the wild or an available patch at this time.

An authenticated student can exploit this vulnerability to access and use another user's block configuration, including those of administrators. This can lead to exposure of sensitive administrator-only data, unauthorized changes to AI model behavior, and potential abuse of API resources. The vulnerability does not impact system availability or integrity directly but compromises confidentiality and proper access control.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, restrict access to the OpenAI Chat Block plugin to trusted users only and monitor for unusual activity related to blockId parameter usage. Avoid granting unnecessary privileges to students and consider disabling the plugin if feasible until patched.