meum Tutor LMS Plugin up to 4.0.7 on WordPress AJAX Action handle_delete improper authorization

Summaryinfo

A vulnerability classified as problematic has been found in meum Tutor LMS Plugin up to 4.0.7. Affected by this issue is the function QuizBuilder::save_questions/QuizBuilder::save_question_answers/QuizBuilder::handle_delete of the component AJAX Action. The manipulation of the argument question_id/answer_id/deleted_question_ids/deleted_answer_ids leads to improper authorization. This vulnerability is referenced as CVE-2026-18439. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability was found in meum Tutor LMS Plugin up to 4.0.7. It has been rated as problematic. This issue affects the function QuizBuilder::save_questions/QuizBuilder::save_question_answers/QuizBuilder::handle_delete of the component AJAX Action. The manipulation of the argument question_id/answer_id/deleted_question_ids/deleted_answer_ids with an unknown input leads to a improper authorization vulnerability. Using CWE to declare the problem leads to CWE-285. The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action. Impacted is integrity, and availability. The summary by CVE is:

The Tutor LMS – eLearning and online course solution plugin for WordPress is vulnerable to Insecure Direct Object Reference in versions up to, and including, 4.0.7 via the tutor_quiz_builder_save AJAX action due to missing validation that nested question_id, answer_id, deleted_question_ids[], and deleted_answer_ids[] values in the submitted payload belong to a quiz/topic/course the requester is authorized to manage. The handler only validates the top-level course_id, topic_id, and (when supplied) payload['ID'], but the nested identifiers are passed straight into $wpdb->update/DELETE statements in QuizBuilder::save_questions(), QuizBuilder::save_question_answers(), and QuizBuilder::handle_delete(). This makes it possible for authenticated attackers, with Instructor-level access and above, to overwrite the content and re-parent arbitrary quiz questions/answers belonging to other instructors or administrators, and to delete arbitrary quiz question and answer rows.

The advisory is shared at wordfence.com. The identification of this vulnerability is CVE-2026-18439 since 07/30/2026. The exploitation is known to be easy. The attack may be initiated remotely. The exploitation requires an enhanced level of successful authentication. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 09/22/2026). MITRE ATT&CK project uses the attack technique T1548.002 for this issue.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Type

• WordPress Plugin

Vendor

• meum

Name

• Tutor LMS Plugin

Version

• 4.0.0
• 4.0.1
• 4.0.2
• 4.0.3
• 4.0.4
• 4.0.5
• 4.0.6
• 4.0.7

CPE 2.3info

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CPE 2.2info

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