What is CVE-2026-81339?

CVE-2026-81339 is a medium-severity vulnerability in Masterstudy Lms WordPress Plugin, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 4.3/10. Published 2026-09-23.

How severe is CVE-2026-81339?

Medium severity. CVSS v3 base score is 4.3 out of 10.

Auth bypass in Masterstudy Lms WordPress Plugin

CVE-2026-81339

The MasterStudy LMS WordPress Plugin WordPress plugin before 3.7.50 does not perform a per-object ownership check when returning a quiz attempt result, allowing any authenticated user with a minimal (subscriber) role to read other students' quiz grades, pass/fail status and attempt timestamps by referencing an attempt identifier belonging to another user.

Vulnerability class: IDOR (Insecure Direct Object Reference)

Published 2026-09-23 · last modified 2026-09-23.

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N.

EPSS exploit prediction

EPSS: 0.002 (7.9th percentile), scored 2026-09-24.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 8th percentile — 7.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

The 30-day trend appears once there are two daily scores.

Affected products

Masterstudy Lms WordPress Plugin

Weakness classification (CWE)

CWE-639 — Authorization Bypass Through User-Controlled Key

References

wpscan.com/vulnerability/f027d0b1-5d8a-4e80-adb3-bbf97dc53306/ (technical-description, exploit, vdb-entry)

Frequently asked questions

What is CVE-2026-81339?: CVE-2026-81339 is a medium-severity vulnerability in Masterstudy Lms WordPress Plugin, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 4.3/10. Published 2026-09-23.
How severe is CVE-2026-81339?: Medium severity. CVSS v3 base score is 4.3 out of 10.