CVE-2025-39436: I Draw File Upload Vulnerability

CVE-2025-39436 Overview

CVE-2025-39436 is an Unrestricted Upload of File with Dangerous Type vulnerability (CWE-434) affecting the I Draw WordPress plugin by aidraw. This vulnerability allows attackers to upload malicious files to vulnerable WordPress installations, potentially leading to complete site compromise through arbitrary code execution.

The vulnerability exists due to insufficient file type validation in the upload functionality of the I Draw plugin. Attackers can exploit this weakness to upload files with dangerous extensions, such as PHP web shells, which can then be executed on the server to gain unauthorized access.

Critical Impact

Arbitrary file upload vulnerabilities in WordPress plugins can lead to complete site takeover, data theft, malware distribution, and use of the compromised server for further attacks.

Affected Products

• I Draw WordPress Plugin version 1.0 and earlier
• WordPress installations with the I Draw (idraw) plugin installed

Discovery Timeline

• 2025-04-17 - CVE CVE-2025-39436 published to NVD
• 2026-04-01 - Last updated in NVD database

Technical Details for CVE-2025-39436

Vulnerability Analysis

This vulnerability falls under CWE-434 (Unrestricted Upload of File with Dangerous Type), which occurs when an application allows users to upload files without properly validating the file type, content, or extension. In the context of the I Draw WordPress plugin, the upload functionality fails to adequately restrict which file types can be uploaded to the server.

When exploited, an attacker can upload executable files such as PHP scripts to the web server. Once uploaded, these files can be accessed directly through the web browser, causing the server to execute the malicious code. This can result in remote code execution with the privileges of the web server process, enabling attackers to read sensitive configuration files, modify website content, access the database, or pivot to other systems on the network.

Root Cause

The root cause of this vulnerability is inadequate input validation and file type verification in the I Draw plugin's file upload mechanism. The plugin does not properly restrict uploaded file types through a combination of extension checking, MIME type validation, and content inspection. This allows attackers to bypass any superficial checks that may exist and upload files with dangerous extensions that can be executed server-side.

Attack Vector

An attacker can exploit this vulnerability by crafting a malicious file, such as a PHP web shell, and uploading it through the vulnerable I Draw plugin functionality. The attack typically proceeds as follows:

1. The attacker identifies a WordPress site running the vulnerable I Draw plugin (version 1.0 or earlier)
2. The attacker crafts a malicious PHP file containing a web shell or reverse shell payload
3. The attacker uses the plugin's upload functionality to submit the malicious file
4. Due to insufficient validation, the server accepts and stores the malicious file
5. The attacker accesses the uploaded file directly through its URL, triggering execution of the malicious code
6. The attacker gains remote code execution capabilities on the target server

For technical details on the exploitation mechanism, refer to the Patchstack WordPress Vulnerability Report.

Detection Methods for CVE-2025-39436

Indicators of Compromise

• Presence of unexpected PHP files in WordPress upload directories, particularly in plugin-specific folders
• Web server access logs showing requests to unusual file paths containing .php extensions in upload directories
• Newly created files with suspicious names or obfuscated content in the wp-content/uploads/ directory
• Unexpected outbound connections from the web server to external IP addresses

Detection Strategies

• Monitor file creation events in WordPress upload directories for executable file types (.php, .phtml, .php5, etc.)
• Implement Web Application Firewall (WAF) rules to detect and block file upload attempts containing PHP code
• Review web server access logs for POST requests to the I Draw plugin's upload endpoints followed by GET requests to newly created files
• Deploy file integrity monitoring to detect unauthorized changes to the WordPress installation

Monitoring Recommendations

• Enable verbose logging for the WordPress installation and monitor for suspicious upload activity
• Configure alerts for any new files with executable extensions created in upload directories
• Implement real-time monitoring of web server processes for unexpected child process spawning
• Review authentication logs for brute force attempts that may precede exploitation

How to Mitigate CVE-2025-39436

Immediate Actions Required

• Immediately deactivate and remove the I Draw plugin from all WordPress installations until a patched version is available
• Audit upload directories for any suspicious files that may have been uploaded through this vulnerability
• Review web server access logs for signs of exploitation attempts or successful compromise
• Consider temporarily disabling file upload functionality site-wide if other plugins with similar vulnerabilities are suspected

Patch Information

As of the last update, no patch has been confirmed for this vulnerability. The vulnerability affects I Draw plugin version 1.0 and all prior versions. Website administrators should monitor the Patchstack WordPress Vulnerability Report for updates on available patches.

Until a patch is released, the recommended action is to completely remove the vulnerable plugin from WordPress installations.

Workarounds

• Remove the I Draw plugin entirely from WordPress installations until a security update is available
• Implement server-level file upload restrictions using .htaccess rules to deny execution of PHP files in upload directories
• Deploy a Web Application Firewall (WAF) with rules to block malicious file uploads
• Configure the web server to prevent PHP execution in the wp-content/uploads/ directory

# Apache .htaccess configuration to prevent PHP execution in uploads directory
# Add this to wp-content/uploads/.htaccess

<FilesMatch "\.(?:php[1-7]?|phtml|phar)$">
    Require all denied
</FilesMatch>

# Alternative: Deny all script execution
<Files *.php>
    deny from all
</Files>