CVE-2026-88845: MasterStudy LMS Authentication Bypass Flaw

CVE-2026-88845 Overview

CVE-2026-88845 affects the MasterStudy LMS WordPress plugin in versions before 3.7.50. The plugin fails to perform capability or nonce checks on an administrative maintenance action. Any authenticated user, including low-privilege subscribers, can trigger the action and create published content attributed to their account. The flaw is classified as Missing Authorization [CWE-862] and stems from broken access control on an administrative handler. The vulnerability allows content pollution on affected sites but does not expose confidentiality or availability of underlying data.

Critical Impact
Authenticated low-privilege WordPress users can trigger an administrative maintenance action to publish arbitrary content attributed to their own account.

Affected Products

MasterStudy LMS WordPress Plugin versions prior to 3.7.50
WordPress sites running the MasterStudy LMS plugin with open user registration
Learning Management System deployments using MasterStudy LMS for course delivery

Discovery Timeline

2026-09-24 - CVE-2026-88845 published to NVD
2026-09-24 - Last updated in NVD database

Technical Details for CVE-2026-88845

Vulnerability Analysis

The vulnerability resides in an administrative maintenance action handler within the MasterStudy LMS plugin. The handler is reachable by authenticated users but lacks the capability check that would restrict execution to administrators. It also omits WordPress nonce validation, which would otherwise bind the request to a legitimate administrative session.

As a result, any logged-in user, including a subscriber account created through standard WordPress registration, can invoke the action. The handler proceeds to create published content on the site attributed to the invoking user. Attackers can abuse the behavior to seed spam, SEO-poisoning pages, or phishing lures that appear as legitimate site content.

See the WPScan Vulnerability Report for additional technical context.

Root Cause

The root cause is a Missing Authorization defect [CWE-862]. The maintenance action handler does not verify that the current user possesses an administrative capability such as manage_options. It also omits a check_admin_referer or wp_verify_nonce call. Without these controls, WordPress treats any authenticated request to the endpoint as valid.

Attack Vector

An attacker registers a subscriber account on a vulnerable WordPress site or uses any existing low-privilege account. The attacker then issues a crafted request to the vulnerable administrative action endpoint. The server executes the maintenance routine and creates one or more published posts attributed to the attacker's user ID. No user interaction from an administrator is required.

The vulnerability requires network access to the WordPress site and valid authentication at any privilege tier.

Detection Methods for CVE-2026-88845

Indicators of Compromise

Unexpected published posts or pages authored by subscriber-level or non-editorial user accounts
Spikes in admin-ajax.php or admin-post.php requests from accounts that normally do not access administrative endpoints
New content containing SEO spam, outbound links, or templated marketing text appearing without editorial workflow
Creation of multiple accounts followed shortly by content publication events

Detection Strategies

Audit the WordPress wp_posts table for records where post_status = 'publish' and post_author references users whose role lacks publishing capability
Correlate web server access logs with WordPress user roles to identify low-privilege accounts invoking administrative action endpoints
Enable WordPress audit logging to capture post creation events along with the authenticated user and originating IP address

Monitoring Recommendations

Monitor plugin version inventory to confirm MasterStudy LMS is upgraded to 3.7.50 or later across all WordPress installations
Alert on new user registrations that are followed within minutes by post creation events
Track outbound HTTP requests from the WordPress host to identify content that includes attacker-controlled links or redirects

How to Mitigate CVE-2026-88845

Immediate Actions Required

Upgrade the MasterStudy LMS WordPress plugin to version 3.7.50 or later on all affected sites
Review the wp_posts table and remove unauthorized posts created by non-editorial accounts
Audit the user list and disable or delete suspicious subscriber accounts created during the exposure window

Patch Information

The vendor addressed the vulnerability in MasterStudy LMS version 3.7.50 by adding capability and nonce checks to the affected administrative maintenance action. Site administrators should apply the update through the WordPress plugin manager or by replacing the plugin files with the patched release. Refer to the WPScan Vulnerability Report for advisory details.

Workarounds

Disable the MasterStudy LMS plugin until the patched version can be deployed if immediate upgrade is not feasible
Restrict new user registration by setting Anyone can register to disabled under WordPress General Settings to limit the attacker pool
Deploy a Web Application Firewall rule that blocks requests to the vulnerable administrative action handler from accounts lacking the edit_posts capability

bash

# Configuration example: disable open registration via WP-CLI
wp option update users_can_register 0

# Verify installed MasterStudy LMS plugin version
wp plugin get masterstudy-lms-learning-management-system --field=version

# Update MasterStudy LMS to the patched release
wp plugin update masterstudy-lms-learning-management-system --version=3.7.50