CVE-2025-54699: Masteriyo LMS Stored XSS Vulnerability

CVE-2025-54699 Overview

CVE-2025-54699 is a stored Cross-Site Scripting (XSS) vulnerability in the Masteriyo LMS WordPress plugin (learning-management-system). The flaw stems from improper neutralization of user-supplied input during web page generation [CWE-79]. The vulnerability affects all versions of Masteriyo LMS up to and including 1.18.3. Authenticated attackers with low privileges can inject malicious scripts that persist in the application and execute in the browsers of other users who view the affected content. Because the scope is changed, successful exploitation can impact resources beyond the vulnerable component, including WordPress administrator sessions.

Critical Impact
Authenticated attackers can inject persistent JavaScript payloads that execute in victims' browsers, enabling session hijacking, credential theft, and administrative account compromise.

Affected Products

Masteriyo LMS WordPress plugin (learning-management-system) versions through 1.18.3
WordPress sites running the vulnerable plugin with user registration enabled
Learning management deployments relying on Masteriyo for course delivery

Discovery Timeline

2025-08-14 - CVE-2025-54699 published to the National Vulnerability Database (NVD)
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-54699

Vulnerability Analysis

The vulnerability is a stored XSS flaw in the Masteriyo LMS plugin for WordPress. Stored XSS occurs when user-controlled input is persisted by the application and later rendered to other users without proper encoding or sanitization. In this case, input fields exposed by the plugin accept data from authenticated users and store it in the WordPress database. When the stored content is rendered in administrative or course-related views, embedded script content executes in the context of the viewing user's browser session.

Exploitation requires user interaction, meaning a victim must view the page containing the injected payload. The attack path typically targets instructors or administrators who manage student submissions, profiles, or course content. Successful execution allows the attacker to perform any action the victim is authorized to perform within the WordPress environment.

Root Cause

The root cause is missing or insufficient output encoding and input sanitization in plugin code paths that render user-supplied data. The plugin fails to apply WordPress sanitization functions such as wp_kses(), esc_html(), or esc_attr() to fields that are later written into the DOM. This allows HTML and JavaScript delivered through plugin inputs to be interpreted as code rather than text.

Attack Vector

An authenticated attacker with low privileges, typically a student or subscriber role, submits a crafted payload through a plugin-exposed input such as a profile field, course interaction, or form submission. The payload is stored in the WordPress database. When an administrator or another authenticated user visits the page that renders the stored data, the injected script executes under their session. This enables session token theft, forced actions via the WordPress REST API, defacement, or privilege escalation through administrative action abuse.

For technical specifics, refer to the Patchstack Security Advisory.

Detection Methods for CVE-2025-54699

Indicators of Compromise

WordPress database entries in Masteriyo tables containing <script>, onerror=, onload=, or javascript: strings
Unexpected outbound requests from administrator browsers to attacker-controlled domains following access to Masteriyo pages
Creation of new administrator accounts or unexpected role changes shortly after an admin views course or student content
Modified plugin settings or new REST API tokens issued without a legitimate administrative action

Detection Strategies

Review Masteriyo-related post meta and custom tables for HTML entities and script tags using targeted SQL queries
Monitor WordPress audit logs for user creation, role changes, and option updates correlated with admin page views
Deploy Content Security Policy (CSP) reporting to surface inline script execution attempts in administrative contexts
Correlate web server access logs for POST requests to Masteriyo endpoints originating from low-privilege accounts

Monitoring Recommendations

Enable WordPress security plugin logging for all actions performed under administrator sessions
Alert on anomalous JavaScript execution patterns in browser telemetry for workstations used by site administrators
Track plugin version inventory across managed WordPress sites to identify installations still running 1.18.3 or earlier

How to Mitigate CVE-2025-54699

Immediate Actions Required

Update the Masteriyo LMS plugin to a version later than 1.18.3 as soon as a patched release is confirmed by the vendor
Audit all Masteriyo-managed content and user profile fields for stored script payloads and remove any injected content
Rotate credentials and session tokens for administrator and instructor accounts that may have viewed malicious content
Restrict user registration and course enrollment to trusted sources until the plugin is updated

Patch Information

The vulnerability affects Masteriyo LMS through version 1.18.3. Consult the Patchstack Security Advisory and the official Masteriyo plugin repository for the fixed version and upgrade instructions.

Workarounds

Temporarily disable the Masteriyo LMS plugin if an upgrade cannot be applied immediately
Deploy a Web Application Firewall (WAF) rule that blocks requests containing script tags or JavaScript event handlers targeting Masteriyo endpoints
Enforce a strict Content Security Policy that disallows inline scripts on WordPress administrative pages
Restrict low-privilege user roles from accessing Masteriyo input fields known to be rendered in administrative views

bash

# Example WordPress CLI commands to inventory and disable the vulnerable plugin
wp plugin list --name=learning-management-system --fields=name,status,version
wp plugin deactivate learning-management-system