---
id: CVE-2026-18439
title: >-
  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 tha…
summary: >-
  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 tha…
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N'
cwe:
  - CWE-639
vendor: themeum
product: Tutor LMS – eLearning and online course solution
affected:
  - tutor_lms_elearning_and_online_course_solution <= 4.0.7
published: '2026-09-22'
updated: '2026-09-23'
sourceUpdated: '2026-09-23T19:17:29.350'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-18439'
references:
  - url: >-
      https://plugins.trac.wordpress.org/browser/tutor/tags/3.9.10/classes/QuizBuilder.php#L156
    label: security@wordfence.com
  - url: >-
      https://plugins.trac.wordpress.org/browser/tutor/tags/3.9.10/classes/QuizBuilder.php#L291
    label: security@wordfence.com
  - url: >-
      https://plugins.trac.wordpress.org/browser/tutor/tags/3.9.10/classes/QuizBuilder.php#L423
    label: security@wordfence.com
  - url: >-
      https://plugins.trac.wordpress.org/browser/tutor/tags/3.9.10/classes/QuizBuilder.php#L430
    label: security@wordfence.com
  - url: >-
      https://plugins.trac.wordpress.org/browser/tutor/tags/3.9.10/classes/QuizBuilder.php#L781
    label: security@wordfence.com
  - url: >-
      https://plugins.trac.wordpress.org/browser/tutor/tags/4.0.3/classes/QuizBuilder.php#L156
    label: security@wordfence.com
  - url: >-
      https://plugins.trac.wordpress.org/browser/tutor/tags/4.0.3/classes/QuizBuilder.php#L291
    label: security@wordfence.com
  - url: >-
      https://plugins.trac.wordpress.org/browser/tutor/tags/4.0.3/classes/QuizBuilder.php#L423
    label: security@wordfence.com
  - url: >-
      https://plugins.trac.wordpress.org/browser/tutor/tags/4.0.3/classes/QuizBuilder.php#L430
    label: security@wordfence.com
  - url: >-
      https://plugins.trac.wordpress.org/browser/tutor/tags/4.0.3/classes/QuizBuilder.php#L781
    label: security@wordfence.com
  - url: >-
      https://plugins.trac.wordpress.org/changeset/3690454/tutor/tags/4.0.8/classes/QuizBuilder.php
    label: security@wordfence.com
  - url: >-
      https://www.wordfence.com/threat-intel/vulnerabilities/id/6d07c82d-262a-4ac1-9ee5-7ef4d025f66f?source=cve
    label: security@wordfence.com
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-23T18:37:32.518219Z'
epss: 0.0025
epssPercentile: 0.1459
ingestedAt: '2026-09-22T08:00:27.694Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.