# CVE-2026-81339: MasterStudy LMS WordPress Plugin insecure direct object reference in quiz attempts

Source: https://junglewise.ai/threats/cve-2026-81339-the-masterstudy-lms-wordpress-plugin-wordpress-plugin-before-3-7  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-23. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-81339 · Severity: medium · CVSS 4.3 · Published 2026-09-23

MasterStudy LMS is a WordPress plugin that provides learning management system functionality for online courses and quizzes. The plugin fails to verify that a user owns a quiz attempt before returning its results, allowing any logged-in student to view other students' quiz grades, pass/fail status, and attempt timestamps by simply guessing or iterating through attempt identifiers. This exposes sensitive academic performance data to unauthorized users.

Vendors: [MasterStudy](https://junglewise.ai/threats/vendors/masterstudy).

## Quick answers

**Is CVE-2026-81339 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-81339 being exploited in the wild.

**How severe is CVE-2026-81339?** Medium severity, with a CVSS score of 4.3, published 23 September 2026.

**Which products and versions are affected?** MasterStudy LMS WordPress Plugin before 3.7.50.

**Is there a fix for CVE-2026-81339?** A patch was published on 2026-09-23: Fixed in version 3.7.50 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-81339 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-81339?** Check whether you run MasterStudy LMS WordPress Plugin at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability is an insecure direct object reference (IDOR) in the quiz attempt results endpoint that lacks per-object ownership validation. An authenticated user with the subscriber role can enumerate quiz attempt IDs and retrieve another user's quiz attempt data including grades, pass/fail status, and attempt timestamps. No network-level attack vector is required beyond normal authenticated access to the WordPress site; the attacker needs only valid login credentials at the subscriber level or above.

## Affected products

- MasterStudy LMS WordPress Plugin before 3.7.50

## Timeline

- 2026-09-23: disclosed: CVE-2026-81339 published
- 2026-09-23: patched: Fixed in version 3.7.50

## References

- [https://wpscan.com/vulnerability/f027d0b1-5d8a-4e80-adb3-bbf97dc53306/](https://wpscan.com/vulnerability/f027d0b1-5d8a-4e80-adb3-bbf97dc53306/)