# CVE-2026-81342: MasterStudy LMS open redirect in user registration

Source: https://junglewise.ai/threats/cve-2026-81342-masterstudy-lms-open-redirect-in-user-registration  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-29. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-81342 · Severity: medium · CVSS 4.7 · Published 2026-08-29

MasterStudy LMS is a learning management system plugin for WordPress used to manage online courses and student registrations. The plugin fails to validate redirect URLs during user registration, allowing attackers to trick users into visiting malicious external websites by sending them trusted-looking links from the victim's site. This could enable phishing attacks that compromise student or instructor credentials.

## Quick answers

**Is CVE-2026-81342 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-81342 being exploited in the wild.

**How severe is CVE-2026-81342?** Medium severity, with a CVSS score of 4.7, published 29 August 2026.

**Which products and versions are affected?** MasterStudy LMS before 3.7.43.

**Is there a fix for CVE-2026-81342?** A patch was published on 2026-08-29: Fixed in version 3.7.43 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-81342 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-81342?** Check whether anything you run is named in the advisory. 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 open redirect (CWE-601) in the user registration flow. The plugin accepts a redirect_page parameter in the registration AJAX endpoint (action=stm_lms_register) without validating that it points to a same-origin URL. An unauthenticated attacker can craft a registration request with an arbitrary external URL in the redirect_page field, which is then used to redirect the user after email confirmation. Prerequisites include: registration must be open, email confirmation (user pre-moderation) must be enabled, and the attacker needs the registration nonce (publicly disclosed in the registration form). When a victim clicks the confirmation link, they are redirected to the attacker's malicious site. The vulnerability was fixed in version 3.7.43.

## Affected products

- MasterStudy LMS before 3.7.43

## Timeline

- 2026-08-27: disclosed
- 2026-08-29: patched: Fixed in version 3.7.43

## References

- [https://wpscan.com/vulnerability/f6f89b50-3087-4fb6-ba12-93fdc1bcc9ed/](https://wpscan.com/vulnerability/f6f89b50-3087-4fb6-ba12-93fdc1bcc9ed/)