CVE-2025-6747

Executive Summary

CVE-2025-6747 is a Stored Cross-Site Scripting (XSS) vulnerability in the Avada (Fusion) Builder plugin for WordPress, affecting all versions up to and including 3.12.1. The flaw resides in the fusion_map shortcode, where insufficient input sanitization and output escaping on user-supplied attributes allow authenticated attackers with contributor-level access or higher to inject arbitrary web scripts. These scripts execute whenever a victim accesses the compromised page, leading to potential session hijacking, credential theft, or defacement. The vulnerability is classified as a WordPress ecosystem issue and does not involve Apache or Nginx. No public proof-of-concept (PoC) or exploit code is available, and the vendor has not issued a patch.

Supply Chain & Package Security

This vulnerability affects the Avada (Fusion) Builder plugin, a commercial WordPress plugin distributed via the Themeforest marketplace. As a third-party component, it introduces supply chain risk: users must rely on the vendor for updates, and no official patch exists. Organizations using this plugin should monitor for updates and consider temporary mitigation measures.

CVSS Breakdown & Threat Level

• CVSS Score: 6.4 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: Low (contributor-level)
• User Interaction: None
• Scope: Changed (impact on other components)
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: None
• Threat Level: Medium – Exploitation requires authenticated access but can lead to persistent compromise of user sessions and data.

Deep Dive & Mechanics

The vulnerability exists in the fusion_map shortcode, which is part of the Avada (Fusion) Builder plugin. This shortcode allows users to embed interactive maps with custom attributes. The plugin fails to properly sanitize and escape user-supplied attributes before rendering them in the HTML output. An attacker with contributor-level access (or higher) can craft a post or page containing the fusion_map shortcode with malicious JavaScript payloads in attributes such as map_style, marker_title, or infobox_content. When the page is viewed by any user (including administrators), the injected script executes in the context of the victim's browser.

The attack flow:

1. Attacker logs in with contributor-level credentials.
2. Creates a new post or page and inserts the fusion_map shortcode with a malicious attribute (e.g., map_style="<script>alert('XSS')</script>").
3. Publishes or saves the post as a draft.
4. Victim (e.g., admin or visitor) accesses the page.
5. The injected script executes, potentially stealing cookies, redirecting to phishing sites, or performing actions on behalf of the victim.

Vulnerable vs. Patched Code

Since no official patch exists, the vulnerable code is present in all versions up to 3.12.1. The following is a hypothetical example of the vulnerable shortcode handler:

Vulnerable Code (fusion_map shortcode handler):

function fusion_map_shortcode($atts) {
    $map_style = $atts['map_style'];
    return '<div class="fusion-map" style="' . $map_style . '">...</div>';
}

Patched Code (hypothetical):

function fusion_map_shortcode($atts) {
    $map_style = esc_attr($atts['map_style']);
    return '<div class="fusion-map" style="' . $map_style . '">...</div>';
}

The patched version uses esc_attr() to escape the attribute value, preventing script injection.

Exploitation & Lab Setup

Red Team

Prerequisites:

• WordPress instance with Avada (Fusion) Builder plugin version <= 3.12.1.
• Contributor-level account credentials.

Steps:

1. Log in to WordPress as a contributor.
2. Create a new post.
3. Insert the fusion_map shortcode with a malicious attribute:

   [fusion_map map_style="background: url('x') onerror='alert(1)'"]
   

4. Publish the post.
5. Wait for an admin or visitor to view the page.

Expected Result: The injected JavaScript executes in the victim's browser.

Blue Team

Detection:

• Monitor for posts containing the fusion_map shortcode with suspicious attributes.
• Use web application firewalls (WAF) to block common XSS payloads in shortcode attributes.
• Restrict contributor-level access to trusted users only.

Mitigation:

• Disable the fusion_map shortcode via WordPress filters if not needed.
• Apply input validation and output escaping manually via a custom plugin or theme functions.

Indicators of Compromise (IOCs)

• File Indicators: Modified WordPress posts/pages containing the fusion_map shortcode with unusual attribute values (e.g., <script>, onerror, javascript:).
• Network Indicators: HTTP requests to the WordPress site with fusion_map in the POST data and suspicious attribute strings.
• Log Indicators: WordPress audit logs showing creation or editing of posts by contributor-level users with shortcode usage.

Detection Engineering

YARA Rule

rule CVE_2025_6747_Avada_XSS {
    meta:
        description = "Detects stored XSS payloads in Avada Fusion Builder fusion_map shortcode"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-6747"
    strings:
        $shortcode = /\[fusion_map[^\]]*\]/ nocase
        $xss_payload = /(<script|<img|<svg|onerror|onload|javascript:)/ nocase
    condition:
        $shortcode and $xss_payload
}

Sigma Rule

title: CVE-2025-6747 Avada Fusion Builder Stored XSS
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects stored XSS attempts via fusion_map shortcode in WordPress
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: 'fusion_map'
        http.body|contains|any:
            - '<script'
            - 'onerror'
            - 'onload'
            - 'javascript:'
    condition: selection
falsepositives:
    - Legitimate use of fusion_map with safe attributes
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-6747 Avada Fusion Builder Stored XSS Attempt"; flow:to_server,established; content:"fusion_map"; http_client_body; pcre:"/(<script|<img|<svg|onerror|onload|javascript:)/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the fusion_map shortcode by adding the following to your theme's functions.php:

   remove_shortcode('fusion_map');
   

2. Restrict contributor-level access to only trusted users.
3. Implement a Web Application Firewall (WAF) rule to block XSS payloads in shortcode attributes.

Long-term Fix:

• Monitor the Avada vendor for an official patch. If none is released, consider replacing the plugin with an alternative.
• Apply input validation and output escaping manually via a custom plugin that hooks into the shortcode.

Valters IT – Securing digital ecosystems through proactive threat intelligence.