CVE-2026-18439: CWE-639 Authorization Bypass Through User-Controlled Key in themeum Tutor LMS – eLearning and online course solution
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.
AI Analysis
Technical Summary
CVE-2026-18439 describes an Insecure Direct Object Reference (IDOR) vulnerability in the Tutor LMS WordPress plugin (versions up to 4.0.7). The vulnerability arises because the AJAX handler for tutor_quiz_builder_save validates only top-level course_id, topic_id, and payload['ID'], but fails to validate nested identifiers such as question_id, answer_id, deleted_question_ids[], and deleted_answer_ids[]. These nested IDs are used directly in database update and delete operations without verifying that they belong to a quiz/topic/course the requester is authorized to manage. Consequently, authenticated users with Instructor-level privileges or higher can overwrite or delete quiz questions and answers belonging to other instructors or administrators.
Potential Impact
The vulnerability allows authenticated users with Instructor-level access or above to modify or delete quiz questions and answers that they should not have permission to manage. This can lead to unauthorized content alteration or removal within the LMS, potentially disrupting course integrity and assessment accuracy. There is no indication of confidentiality or availability impact beyond content integrity.
Mitigation Recommendations
No official patch or fix information is provided in the available data. Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, restrict Instructor-level access carefully and monitor for suspicious activity related to quiz content modifications.
CVE-2026-18439: CWE-639 Authorization Bypass Through User-Controlled Key in themeum Tutor LMS – eLearning and online course solution
Description
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.
CVSS v3.1
Score 4.3medium
Affected software
themeum
Tutor LMS – eLearning and online course solution
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-18439 describes an Insecure Direct Object Reference (IDOR) vulnerability in the Tutor LMS WordPress plugin (versions up to 4.0.7). The vulnerability arises because the AJAX handler for tutor_quiz_builder_save validates only top-level course_id, topic_id, and payload['ID'], but fails to validate nested identifiers such as question_id, answer_id, deleted_question_ids[], and deleted_answer_ids[]. These nested IDs are used directly in database update and delete operations without verifying that they belong to a quiz/topic/course the requester is authorized to manage. Consequently, authenticated users with Instructor-level privileges or higher can overwrite or delete quiz questions and answers belonging to other instructors or administrators.
Potential Impact
The vulnerability allows authenticated users with Instructor-level access or above to modify or delete quiz questions and answers that they should not have permission to manage. This can lead to unauthorized content alteration or removal within the LMS, potentially disrupting course integrity and assessment accuracy. There is no indication of confidentiality or availability impact beyond content integrity.
Mitigation Recommendations
No official patch or fix information is provided in the available data. Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, restrict Instructor-level access carefully and monitor for suspicious activity related to quiz content modifications.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- Wordfence
- Date Reserved
- 2026-07-30T20:23:23.648Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6ab23644f7a7c54106e04242
Added to database: 09/22/2026, 08:03:16 UTC
Last enriched: 09/22/2026, 08:19:18 UTC
Last updated: 09/23/2026, 01:58:07 UTC
Views: 16
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