CVE-2025-0394: Groundhogg WordPress Plugin RCE Vulnerability

CVE-2025-0394 Overview

CVE-2025-0394 affects the Groundhogg CRM, Email & Marketing Automation plugin for WordPress. The vulnerability allows authenticated attackers with Author-level access or higher to upload arbitrary files to the server. The flaw resides in the gh_big_file_upload() function, which fails to validate file types before accepting uploads. Successful exploitation can lead to remote code execution on the affected WordPress site. All plugin versions up to and including 3.7.3.5 are vulnerable. The issue is tracked under CWE-434 (Unrestricted Upload of File with Dangerous Type).

Critical Impact
Authenticated attackers with Author-level access can upload arbitrary files, including PHP webshells, enabling remote code execution and full site compromise.

Affected Products

Groundhogg plugin for WordPress, versions up to and including 3.7.3.5
WordPress sites running the vulnerable big-file-uploader.php component
Any WordPress installation where Author-level (or higher) accounts are accessible to untrusted users

Discovery Timeline

2025-01-14 - CVE-2025-0394 published to the National Vulnerability Database (NVD)
2026-06-17 - Last updated in the NVD database

Technical Details for CVE-2025-0394

Vulnerability Analysis

The vulnerability is an Unrestricted File Upload flaw in the Groundhogg WordPress plugin. The plugin exposes a chunked or large-file upload handler implemented in gh_big_file_upload() inside includes/big-file-uploader.php. The handler accepts file content from authenticated users but omits a server-side file type or extension check before persisting the file. An attacker holding an Author-level account can therefore upload executable PHP files into a web-accessible directory. Once written, the attacker requests the file through the web server, triggering PHP execution under the WordPress process context.

The attack scope covers confidentiality, integrity, and availability because remote code execution gives the attacker full control of the WordPress application, its database credentials, and any files reachable by the PHP process.

Root Cause

The gh_big_file_upload() function in includes/big-file-uploader.php does not enforce a MIME type allowlist, extension blocklist, or content inspection step. WordPress provides helpers such as wp_check_filetype_and_ext() and wp_handle_upload() that perform these checks, but the affected code path bypasses them. The fix landed in changeset 3221208 and adds file type validation to the upload handler.

Attack Vector

The attack vector is network-based and requires a valid authenticated session with Author privileges or higher. An attacker submits a crafted multipart upload request to the Groundhogg big-file upload endpoint with a PHP payload, for example shell.php containing a webshell. Because no extension or MIME check occurs, the file lands in the uploads directory. The attacker then issues an HTTP GET request to the uploaded file, executing arbitrary commands on the underlying host.

No public proof-of-concept exploit is currently available, and the vulnerability is not listed on the CISA Known Exploited Vulnerabilities catalog. Technical detail is available in the WordPress Plugin Code Review and the Wordfence Vulnerability Report.

Detection Methods for CVE-2025-0394

Indicators of Compromise

Unexpected .php, .phtml, or .phar files in the WordPress wp-content/uploads/ directory or Groundhogg-specific upload paths
POST requests to Groundhogg big-file upload endpoints from Author-level accounts followed by direct GET requests to newly created files
New or modified PHP files with timestamps that align with recent authenticated sessions from low-privilege accounts
Outbound network connections from the web server process (php-fpm, apache2, www-data) to unfamiliar hosts shortly after an upload

Detection Strategies

Monitor the web server access log for sequences of upload requests to Groundhogg endpoints followed by execution of files in writable directories
Inspect filesystem events for PHP file creation under upload directories using file integrity monitoring
Correlate WordPress audit logs with Author or Editor account activity that includes file upload actions outside the expected media library workflow
Hunt for webshell signatures and obfuscated PHP (eval, base64_decode, assert, system) inside the uploads tree

Monitoring Recommendations

Forward WordPress, PHP-FPM, and web server logs to a centralized analytics platform for correlation
Alert on creation of executable file extensions in any directory that should hold only static media
Track privilege use by Author-level and above accounts, flagging accounts that suddenly begin uploading files
Baseline normal Groundhogg upload behavior and alert on deviations in file size, type, or frequency

How to Mitigate CVE-2025-0394

Immediate Actions Required

Upgrade the Groundhogg plugin to a version later than 3.7.3.5 that includes the fix from changeset 3221208
Audit all Author-level and above accounts, removing or resetting credentials for accounts that should not exist
Scan wp-content/uploads/ and Groundhogg upload paths for unauthorized PHP files and remove them
Rotate WordPress secret keys, database credentials, and API tokens if compromise is suspected

Patch Information

The vendor patched the issue in the Groundhogg plugin after version 3.7.3.5. The fix introduces file type validation in gh_big_file_upload() and is documented in the WordPress Changeset History. Site administrators should update through the WordPress plugin manager or pull the latest release referenced in the Groundhogg developer page.

Workarounds

Disable the Groundhogg plugin until the patched version is installed
Restrict Author-level and higher registration to trusted users only and enforce strong authentication on those accounts
Configure the web server to deny PHP execution within wp-content/uploads/ and other writable directories
Deploy a web application firewall rule that blocks uploads of files with executable extensions to Groundhogg endpoints

bash

# Apache: block PHP execution inside the WordPress uploads directory
# Place this in wp-content/uploads/.htaccess
<FilesMatch "\.(php|phtml|phar|php3|php4|php5|php7|phps)$">
    Require all denied
</FilesMatch>

# Nginx equivalent (server block)
location ~* /wp-content/uploads/.*\.(php|phtml|phar)$ {
    deny all;
    return 403;
}