# CVE-2026-81338: MasterStudy LMS stored HTML injection in course discussions

Source: https://junglewise.ai/threats/cve-2026-81338-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-2026-81338 · Severity: medium · CVSS 4.6 · Published 2026-09-23

MasterStudy LMS is a WordPress plugin that manages online courses and learning platforms. The plugin fails to properly filter user-submitted content in course discussions, allowing students and higher-level users to inject malicious HTML including iframes. Attackers can exploit this to conduct phishing attacks and impersonate site content to deceive other users viewing discussions.

Technologies: [MasterStudy LMS](https://junglewise.ai/threats/technologies/masterstudy-masterstudy-lms). Vendors: [MasterStudy](https://junglewise.ai/threats/vendors/masterstudy).

## Quick answers

**Is CVE-2026-81338 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-81338 being exploited in the wild.

**How severe is CVE-2026-81338?** Medium severity, with a CVSS score of 4.6, published 23 September 2026.

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

**Is there a fix for CVE-2026-81338?** 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-2026-81338 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-81338?** Check whether you run MasterStudy LMS 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 plugin does not sanitize or restrict HTML in user-submitted content before storing and rendering it in course discussions. Subscribers and above-level WordPress users can inject arbitrary HTML and embed iframes, which persists and affects all subsequent viewers. The vulnerability requires user interaction from site visitors viewing the injected content, enabling phishing and content spoofing attacks.

## Affected products

- MasterStudy MasterStudy LMS before 3.7.50

## Timeline

- 2026-09-21: disclosed
- 2026-09-23: patched: Fixed in version 3.7.50

## References

- [https://wpscan.com/vulnerability/e8494c71-fb0f-4ab9-a8b7-8db3745a2d9b/](https://wpscan.com/vulnerability/e8494c71-fb0f-4ab9-a8b7-8db3745a2d9b/)

## Related threats

- [MasterStudy LMS privilege escalation in user enrollment](https://junglewise.ai/threats/cve-2026-88849-the-masterstudy-lms-wordpress-plugin-wordpress-plugin-before-3-7)
- [MasterStudy LMS authorization bypass in course progress recording](https://junglewise.ai/threats/cve-2026-88847-the-masterstudy-lms-wordpress-plugin-wordpress-plugin-before-3-7)
- [MasterStudy LMS WordPress Plugin account creation bypass with registration disabled](https://junglewise.ai/threats/cve-2026-88846-the-masterstudy-lms-wordpress-plugin-wordpress-plugin-before-3-7)
- [MasterStudy LMS WordPress plugin authorization bypass in demo import](https://junglewise.ai/threats/cve-2026-88845-the-masterstudy-lms-wordpress-plugin-wordpress-plugin-before-3-7)