CVE-2021-4455
📋 TL;DR
The Smart Product Review WordPress plugin allows unauthenticated attackers to upload arbitrary files due to missing file type validation. This vulnerability affects all versions up to 1.0.4 and can lead to remote code execution on vulnerable WordPress sites.
💻 Affected Systems
- WordPress Smart Product Review Plugin
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Complete server compromise via remote code execution, allowing attackers to install malware, steal data, or use the server for further attacks.
Likely Case
Attackers upload web shells to gain persistent access, deface websites, or install cryptocurrency miners.
If Mitigated
File uploads are blocked or properly validated, preventing malicious file execution.
🎯 Exploit Status
Exploit code is publicly available and requires minimal technical skill to execute.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.0.5 or later
Vendor Advisory: https://wordpress.org/plugins/smart-product-review/
Restart Required: No
Instructions:
1. Log into WordPress admin panel. 2. Navigate to Plugins → Installed Plugins. 3. Find Smart Product Review plugin. 4. Click 'Update Now' if update available. 5. If no update, deactivate and delete plugin immediately.
🔧 Temporary Workarounds
Disable Plugin
allDeactivate the vulnerable plugin to prevent exploitation.
wp plugin deactivate smart-product-review
Web Server File Upload Restriction
linuxConfigure web server to block file uploads to the plugin directory.
# Apache: Add to .htaccess
<FilesMatch "\.(php|phtml|php3|php4|php5|php7|phps|php-s|pht|phar)">
Order Allow,Deny
Deny from all
</FilesMatch>
# Nginx: Add to server block
location ~* /wp-content/plugins/smart-product-review/.*\.(php|phtml|php3|php4|php5|php7|phps|php-s|pht|phar)$ {
deny all;
}
🧯 If You Can't Patch
- Immediately deactivate and remove the Smart Product Review plugin from all WordPress installations.
- Implement web application firewall (WAF) rules to block file upload attempts to the plugin's endpoints.
🔍 How to Verify
Check if Vulnerable:
Check WordPress admin → Plugins → Installed Plugins for Smart Product Review version 1.0.4 or earlier.Check Version:
wp plugin get smart-product-review --field=versionVerify Fix Applied:
Verify plugin version is 1.0.5 or later, or confirm plugin is deactivated/removed.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /wp-content/plugins/smart-product-review/ upload endpoints
- File uploads of PHP or executable files to plugin directories
- 404 errors for known exploit paths
Network Indicators:
- HTTP POST requests with file uploads to Smart Product Review plugin paths
- Unusual outbound connections from WordPress server after file uploads
SIEM Query:
source="web_server" AND (uri_path="/wp-content/plugins/smart-product-review/" AND method="POST")