CVE Intelligence
Medium Access control

CVE-2026-18439 — Tutor LMS <= 4.0.7 - Authenticated (Custom+) Insecure Direct Object Reference to Arbitrary Quiz Question/Answer Modification and Deletion via 'payload' Parameter

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.

Published Sep 22, 2026 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: Wordfence

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.3% (30-day exploitation probability)+2
  • Technical severity (medium)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.25%
ahead of 15% of scored CVEs · Oct 15, 2026
Affects
Themeum
Tutor LMS – eLearning and online course solution
CVSS base
4.3
Medium · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
None
none · proof-of-concept · active
Automatable
No
can an attacker script the kill-chain steps
Technical impact
Partial
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Themeum Tutor LMS – eLearning and online course solution).
  2. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  3. Search available logs for exploit probes matching the vulnerability class (access control), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Themeum Tutor LMS – eLearning and online course solution ≤ 4.0.7 Vulnerable CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
4.3 CVSS 3.1 Medium 2.8 1.4 security@wordfence.com via NIST National Vulnerability Database
4.3 CVSS 3.1 Medium — — Wordfence via CVE Program (cve.org) e CISA ADP
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N (score shown at the top: security@wordfence.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-639 · Authorization Bypass Through User-Controlled Key (IDOR)

Other CVEs with this weakness →

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
  • Audit administrative actions and access to resources outside each user’s normal pattern.
web/proxy/WAF logsnetwork IDS/IPSauthentication logsapplication logs

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · themeum/tutor lms – elearning and online course solution
    Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 15, 2026
  • CVSS changed · 4.3
    Oct 15, 2026 · NIST National Vulnerability Database
  • Source status changed · → Deferred
    Oct 15, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 15, 2026 · NIST National Vulnerability Database
  • CVE published
    Sep 22, 2026 · Wordfence

Source activity

Repeated readings are counted rather than listed.

  • 1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

12 on the record

Elsewhere on this site

Themeum
every CVE for this vendor
Access control
same class
CWE-639
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-93681 Tutor LMS <= 4.1.0 - Authenticated (Subscriber+) Stored Cross-Site Scripting via display_name Parameter 4h
  • CVE-2026-88963 Tutor LMS <= 4.0.8 - Authenticated (Subscriber+) Reflected DOM-Based Cross-Site Scripting via 'redirect_url' Parameter 7h
  • CVE-2026-100193 Tutor LMS <= 4.1.0 - Reflected Cross-Site Scripting via 'tab' Parameter 2d
  • CVE-2026-89333 Tutor LMS <= 4.0.8 - Insecure Direct Object Reference to Authenticated (Subscriber+) Sensitive Information Exposure via 'student_id' Parameter 27d
  • CVE-2026-88944 Tutor LMS <= 4.0.8 - Missing Authorization to Authenticated (Subscriber+) Arbitrary Post Deletion via 'lesson_id' Parameter 27d
  • CVE-2026-89081 Tutor LMS <= 4.0.8 - Reflected Cross-Site Scripting via 'back_url' and 'search' Parameters 27d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No fixed version, patch or mitigation documented.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-18439 is "Tutor LMS <= 4.0.7 - Authenticated (Custom+) Insecure Direct Object Reference to Arbitrary Quiz Question/Answer Modification and Deletion via 'payload' Parameter", rated Medium. It affects Tutor LMS – eLearning and online course solution (Themeum); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 4.3 describes technical severity. EPSS 0.25% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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