CVE-2025-10041: Flex QR Code Generator RCE Vulnerability

CVE-2025-10041 Overview

The Flex QR Code Generator plugin for WordPress contains a critical arbitrary file upload vulnerability due to missing file type validation in the save_qr_code_to_db() function. This security flaw affects all versions up to and including 1.2.5, enabling unauthenticated attackers to upload arbitrary files to vulnerable WordPress installations. Successful exploitation could lead to remote code execution, allowing threat actors to gain complete control over the affected web server.

Critical Impact

Unauthenticated attackers can upload malicious files including PHP webshells to achieve remote code execution without any user interaction or authentication requirements.

Affected Products

• Flex QR Code Generator WordPress Plugin versions ≤ 1.2.5
• WordPress installations with the vulnerable plugin activated

Discovery Timeline

• October 15, 2025 - CVE-2025-10041 published to NVD
• October 16, 2025 - Last updated in NVD database

Technical Details for CVE-2025-10041

Vulnerability Analysis

This vulnerability is classified as CWE-434 (Unrestricted Upload of File with Dangerous Type). The save_qr_code_to_db() function in the Flex QR Code Generator plugin lacks proper file type validation, creating a direct path for attackers to upload executable files such as PHP scripts. Because the vulnerable endpoint does not require authentication, any remote attacker can exploit this flaw without needing valid credentials or any form of user interaction.

The attack can be conducted entirely over the network with low complexity, making it highly exploitable in real-world scenarios. Once a malicious file is uploaded, an attacker can execute arbitrary code on the server, potentially leading to complete system compromise, data theft, website defacement, or use of the server for further attacks.

Root Cause

The root cause of this vulnerability is the absence of file type validation in the save_qr_code_to_db() function located in qr-code-generator.php. The function accepts file uploads without verifying that the uploaded content matches an expected and safe file type. This allows attackers to bypass intended restrictions and upload dangerous file types such as .php, .phtml, or other server-executable scripts.

Attack Vector

The attack vector is network-based and does not require authentication. An attacker can craft a malicious HTTP request to the vulnerable endpoint, including a file payload disguised or directly submitted as an executable script. The lack of validation means the server will accept and store the file, which can then be accessed via a direct URL to trigger code execution.

The vulnerability can be exploited by sending a specially crafted POST request to the plugin's file upload handler. The malicious file, such as a PHP webshell, is then saved to an accessible location on the WordPress server. For technical details on the vulnerable code, refer to the WordPress Plugin Source Code.

Detection Methods for CVE-2025-10041

Indicators of Compromise

• Unexpected PHP or script files appearing in WordPress upload directories or plugin folders
• Web server access logs showing POST requests to plugin endpoints with unusual file extensions
• New files with recent timestamps in the wp-content/uploads/ or plugin directories that were not created by administrators
• Webshell activity indicators such as command execution or network connections from the web server process

Detection Strategies

• Implement file integrity monitoring to detect unauthorized file additions or modifications in WordPress directories
• Review web server access logs for suspicious POST requests targeting the Flex QR Code Generator plugin endpoints
• Deploy Web Application Firewall (WAF) rules to block file upload attempts containing executable content or suspicious extensions
• Scan WordPress installations for known webshell signatures and malicious PHP files

Monitoring Recommendations

• Enable real-time alerting for new file creation events in WordPress plugin and upload directories
• Monitor for unusual outbound network connections from the web server that may indicate post-exploitation activity
• Implement logging and analysis of all HTTP POST requests to WordPress plugin endpoints
• Regularly audit installed WordPress plugins and their versions against known vulnerability databases

How to Mitigate CVE-2025-10041

Immediate Actions Required

• Immediately deactivate and remove the Flex QR Code Generator plugin if running version 1.2.5 or earlier
• Conduct a thorough security audit of the WordPress uploads directory and plugin folders for any suspicious or unauthorized files
• Review web server and WordPress access logs for evidence of exploitation attempts
• If compromise is suspected, isolate the server, preserve evidence, and perform incident response procedures

Patch Information

Organizations using the Flex QR Code Generator plugin should check for an updated version that addresses this vulnerability. Consult the WordPress Plugin Overview page and the Wordfence Vulnerability Report for the latest patch information and remediation guidance. Until a patched version is available and verified, the plugin should be removed from production environments.

Workarounds

• Completely disable or remove the Flex QR Code Generator plugin until a security patch is released
• Implement server-side restrictions to block execution of PHP files in upload directories using .htaccess or web server configuration
• Deploy a Web Application Firewall with rules to block file upload attacks targeting WordPress plugins
• Restrict access to WordPress admin and plugin endpoints using IP allowlisting where feasible

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

<FilesMatch "\.php$">
    Order Allow,Deny
    Deny from all
</FilesMatch>