CVE-2025-4391: Echo RSS Feed Post Generator RCE Flaw

CVE-2025-4391 Overview

The Echo RSS Feed Post Generator plugin for WordPress contains a critical arbitrary file upload vulnerability due to missing file type validation in the echo_generate_featured_image() function. This vulnerability affects all versions up to and including 5.4.8.1, allowing unauthenticated attackers to upload arbitrary files to the affected site's server, potentially enabling remote code execution.

Critical Impact

Unauthenticated attackers can upload malicious files (such as PHP web shells) to WordPress servers, potentially achieving complete server compromise and remote code execution without any authentication required.

Affected Products

• Echo RSS Feed Post Generator plugin for WordPress versions ≤ 5.4.8.1
• WordPress sites running vulnerable versions of the Echo RSS Feed Post Generator plugin

Discovery Timeline

• 2025-05-17 - CVE-2025-4391 published to NVD
• 2025-05-19 - Last updated in NVD database

Technical Details for CVE-2025-4391

Vulnerability Analysis

This vulnerability is classified as CWE-434 (Unrestricted Upload of File with Dangerous Type). The echo_generate_featured_image() function in the Echo RSS Feed Post Generator plugin fails to properly validate file types before processing uploads. This absence of file type validation creates a direct pathway for attackers to upload executable files, such as PHP scripts, which can then be accessed via the web server to execute arbitrary commands.

The vulnerability is particularly severe because it requires no authentication, meaning any remote attacker can exploit it without needing valid WordPress credentials. Once a malicious file is uploaded, the attacker can execute arbitrary code on the server with the privileges of the web server process.

Root Cause

The root cause of this vulnerability lies in the missing file type validation within the echo_generate_featured_image() function. When the plugin processes featured images from RSS feeds, it does not verify that the uploaded content is actually a legitimate image file. The function lacks checks for:

• File extension validation
• MIME type verification
• Content-based file type detection

This oversight allows attackers to craft malicious requests that upload executable files (such as .php files) disguised as image content.

Attack Vector

The attack can be executed remotely over the network without any user interaction or authentication. An attacker can exploit this vulnerability by:

1. Crafting a malicious HTTP request targeting the vulnerable function
2. Supplying a malicious file (e.g., a PHP web shell) instead of a legitimate image
3. The file is uploaded and stored on the server without validation
4. Accessing the uploaded file via URL to execute arbitrary commands

The vulnerability mechanism involves the plugin's failure to validate file types during the featured image generation process. For detailed technical analysis, refer to the Wordfence Vulnerability Analysis.

Detection Methods for CVE-2025-4391

Indicators of Compromise

• Unexpected PHP files or web shells in WordPress upload directories (typically wp-content/uploads/)
• Unusual file extensions or suspicious filenames in media library directories
• Unauthorized HTTP requests to the plugin's endpoints handling featured image generation
• Web server logs showing requests to newly created PHP files in upload directories

Detection Strategies

• Monitor WordPress upload directories for newly created executable files (.php, .phtml, .phar)
• Implement web application firewall (WAF) rules to detect and block file upload attacks
• Use file integrity monitoring to detect unauthorized changes to the WordPress file system
• Review web server access logs for suspicious POST requests to Echo RSS plugin endpoints

Monitoring Recommendations

• Enable detailed logging for all file upload operations in WordPress
• Configure alerts for creation of executable files in media upload directories
• Monitor outbound connections from the web server that may indicate command and control activity
• Implement real-time file system monitoring on WordPress installations

How to Mitigate CVE-2025-4391

Immediate Actions Required

• Disable or remove the Echo RSS Feed Post Generator plugin immediately if running version 5.4.8.1 or earlier
• Audit WordPress upload directories for any suspicious or unauthorized files
• Review web server logs for evidence of exploitation attempts
• Implement web application firewall rules to block arbitrary file upload attempts
• Check for any unauthorized administrative accounts or backdoors

Patch Information

Check the Echo RSS Feed Post Generator plugin on Codecanyon for the latest security updates. Organizations should update to a patched version as soon as one becomes available from the vendor.

Workarounds

• Temporarily disable the Echo RSS Feed Post Generator plugin until a patch is available
• Implement server-level restrictions to prevent execution of PHP files in upload directories
• Configure .htaccess rules to deny direct access to uploaded files or restrict execution permissions
• Use a Web Application Firewall (WAF) to filter malicious file upload attempts

# Apache .htaccess example to prevent PHP execution in uploads directory
# Add to wp-content/uploads/.htaccess
<FilesMatch "\.(?:php|phtml|php3|php4|php5|phar)$">
    Order Allow,Deny
    Deny from all
</FilesMatch>