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CVE-2023-4278

7.5 HIGH
Authentication Bypass

📋 TL;DR

The MasterStudy LMS WordPress plugin before version 3.0.18 has an improper access control vulnerability that allows unauthenticated attackers to register as instructors on affected sites. This enables unauthorized users to create courses and posts, potentially compromising site integrity and content control. All WordPress sites using vulnerable versions of this plugin are affected.

💻 Affected Systems

Products:
  • MasterStudy LMS WordPress Plugin
Versions: All versions before 3.0.18
Operating Systems: Any OS running WordPress
Default Config Vulnerable: ⚠️ Yes
Notes: Only affects WordPress sites with the MasterStudy LMS plugin installed and enabled.

📦 What is this software?

Masterstudy Lms by Stylemixthemes

View all CVEs affecting Masterstudy Lms →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Attackers gain instructor privileges, create malicious courses/content, deface the site, inject malicious code, or use the platform to distribute malware to students.

🟠

Likely Case

Spammers or low-skill attackers create unauthorized courses/posts, compromising site content quality and potentially exposing users to malicious content.

🟢

If Mitigated

With proper monitoring and quick response, unauthorized accounts can be detected and removed before causing significant damage.

🌐 Internet-Facing: HIGH
🏢 Internal Only: LOW

🎯 Exploit Status

Public PoC: ⚠️ Yes
Weaponized: LIKELY
Unauthenticated Exploit: ⚠️ Yes
Complexity: LOW

Public exploit details available on Packet Storm Security and WPScan. Attack requires no authentication and minimal technical skill.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: 3.0.18

Vendor Advisory: https://wordpress.org/plugins/masterstudy-lms-learning-management-system/#developers

Restart Required: No

Instructions:

1. Log into WordPress admin panel. 2. Navigate to Plugins → Installed Plugins. 3. Find MasterStudy LMS plugin. 4. Click 'Update Now' if available. 5. If manual update needed, download version 3.0.18+ from WordPress.org. 6. Deactivate old plugin. 7. Upload new version via FTP or WordPress uploader. 8. Activate updated plugin.

🔧 Temporary Workarounds

Disable User Registration

all

Temporarily disable all user registration on the WordPress site to prevent exploitation.

Navigate to Settings → General in WordPress admin and uncheck 'Anyone can register'

Deactivate Plugin

all

Temporarily deactivate the MasterStudy LMS plugin until patched.

Navigate to Plugins → Installed Plugins in WordPress admin and click 'Deactivate' under MasterStudy LMS

🧯 If You Can't Patch

  • Implement web application firewall (WAF) rules to block unauthorized registration attempts
  • Enable detailed logging and monitoring for user registration events and new instructor accounts

🔍 How to Verify

Check if Vulnerable:

Check WordPress admin panel → Plugins → Installed Plugins for MasterStudy LMS version. If version is below 3.0.18, you are vulnerable.

Check Version:

wp plugin list --name=masterstudy-lms --field=version (if WP-CLI installed)

Verify Fix Applied:

After updating, verify plugin version shows 3.0.18 or higher in WordPress admin. Test registration functionality to ensure proper instructor role checks.

📡 Detection & Monitoring

Log Indicators:

  • Unusual spike in user registrations
  • New users with instructor/capabilities roles
  • Registration attempts from unexpected IPs/regions

Network Indicators:

  • POST requests to registration endpoints without proper authentication
  • Multiple registration attempts in short time

SIEM Query:

source="wordpress.log" AND ("user_registered" OR "new_user") AND ("role=instructor" OR "capabilities=instructor")

📊 Metadata

CVE ID: CVE-2023-4278
CVSS v3 Score: 7.5 (HIGH)
CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Published: September 11, 2023
Last Updated: April 23, 2025

🔗 References

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