CVE-2025-3917 Overview
CVE-2025-3917 is a critical arbitrary file upload vulnerability affecting the 百度站长SEO合集 (BaiduSEO) plugin for WordPress. The vulnerability exists due to missing file type validation in the download_remote_image_to_media_library function in all versions up to and including 2.0.6. This security flaw enables unauthenticated attackers to upload arbitrary files to the affected site's server, potentially leading to remote code execution.
Critical Impact
Unauthenticated attackers can upload malicious files to WordPress servers, potentially achieving complete site compromise through remote code execution without requiring any user interaction or authentication.
Affected Products
- 百度站长SEO合集 (BaiduSEO) WordPress Plugin versions up to and including 2.0.6
- WordPress installations with the vulnerable BaiduSEO plugin active
- Any web server hosting WordPress with this plugin installed
Discovery Timeline
- May 15, 2025 - CVE-2025-3917 published to NVD
- May 16, 2025 - Last updated in NVD database
Technical Details for CVE-2025-3917
Vulnerability Analysis
This vulnerability is classified as CWE-434 (Unrestricted Upload of File with Dangerous Type). The core issue resides in the download_remote_image_to_media_library function located in the youhua.php file within the plugin's codebase. The function fails to implement proper file type validation when processing remotely downloaded files, allowing attackers to bypass intended restrictions and upload executable files such as PHP web shells.
The vulnerability is particularly severe because it requires no authentication to exploit. An attacker can craft malicious requests targeting the vulnerable function and upload arbitrary files directly to the WordPress media library without needing valid credentials or session tokens.
Root Cause
The root cause of this vulnerability is the absence of file type validation in the download_remote_image_to_media_library function. When the function downloads a remote file, it does not verify that the file's MIME type or extension corresponds to legitimate image formats. This allows an attacker to specify a URL pointing to a malicious PHP file (or other executable content), which the function will download and store in the WordPress media directory without restriction.
Proper secure coding practices would require validation of both the file extension and MIME type, along with content inspection to ensure the uploaded file matches expected image signatures.
Attack Vector
The attack can be executed remotely over the network without any authentication requirements. An attacker would craft a malicious HTTP request to the vulnerable endpoint, providing a URL parameter pointing to a remote server hosting a malicious file (such as a PHP web shell). The vulnerable function downloads this file and saves it to the WordPress media library.
Once uploaded, the attacker can directly access the malicious file via its public URL, achieving arbitrary code execution on the target server. This attack pattern is commonly used to deploy web shells, cryptocurrency miners, or as an initial foothold for further lateral movement within the compromised environment.
The vulnerable code can be reviewed in the WordPress Plugin Code Repository.
Detection Methods for CVE-2025-3917
Indicators of Compromise
- Unexpected PHP files or other executable scripts appearing in the wp-content/uploads/ directory
- Web server access logs showing requests to the vulnerable plugin endpoint with external URL parameters
- Presence of web shell files with obfuscated or encoded content in media directories
- Unusual outbound network connections from the web server to unknown external hosts
Detection Strategies
- Monitor WordPress media upload directories for files with executable extensions (.php, .phtml, .php5, .phar)
- Implement Web Application Firewall (WAF) rules to detect and block requests containing external URLs targeting the vulnerable endpoint
- Review web server access logs for suspicious POST requests to /wp-content/plugins/baiduseo/ paths
- Deploy file integrity monitoring on WordPress installations to detect unauthorized file additions
Monitoring Recommendations
- Enable real-time file system monitoring for the WordPress wp-content/uploads/ directory
- Configure alerts for any new PHP file creation within media upload directories
- Implement logging and alerting for requests matching the vulnerable function's endpoint patterns
- Regularly audit installed WordPress plugins against known vulnerability databases
How to Mitigate CVE-2025-3917
Immediate Actions Required
- Immediately deactivate and remove the 百度站长SEO合集 (BaiduSEO) plugin if running version 2.0.6 or earlier
- Conduct a thorough audit of the wp-content/uploads/ directory for any suspicious or unexpected files
- Review web server access logs for evidence of exploitation attempts
- Consider restoring from a known-clean backup if compromise is suspected
Patch Information
As of the last modification date, users should check the official WordPress plugin page for updated versions that address this vulnerability. Additional technical details and vulnerability information can be found in the Wordfence Vulnerability Report.
Workarounds
- Temporarily disable the plugin until a patched version is available
- Implement server-level restrictions to prevent PHP execution in upload directories
- Deploy a Web Application Firewall (WAF) with rules to block arbitrary file upload attempts
- Restrict network access to the WordPress admin and plugin endpoints where feasible
# Disable PHP execution in WordPress uploads directory (Apache)
# Add to .htaccess file in wp-content/uploads/
<FilesMatch "\.php$">
Order Deny,Allow
Deny from all
</FilesMatch>
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
