CVE-2021-24916
📋 TL;DR
The Qubely WordPress plugin before version 1.8.6 contains an unauthenticated email injection vulnerability. Unauthenticated attackers can send arbitrary emails to any recipient address via the qubely_send_form_data AJAX action. This affects all WordPress sites running vulnerable versions of the Qubely plugin.
💻 Affected Systems
- Qubely WordPress Plugin
📦 What is this software?
Qubely by Themeum
⚠️ Risk & Real-World Impact
Worst Case
Attackers could send phishing emails, spam, or malicious content appearing to originate from the legitimate site, potentially damaging reputation and enabling further social engineering attacks.
Likely Case
Spam campaigns, phishing attempts, or email harassment using the vulnerable site's email infrastructure.
If Mitigated
Limited to email system abuse without direct access to sensitive data or system compromise.
🎯 Exploit Status
Simple HTTP POST request to the vulnerable AJAX endpoint with crafted parameters.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.8.6
Vendor Advisory: https://wpscan.com/vulnerability/93b893be-59ad-4500-8edb-9fa7a45304d5
Restart Required: No
Instructions:
1. Log into WordPress admin panel. 2. Navigate to Plugins > Installed Plugins. 3. Find Qubely plugin. 4. Click 'Update Now' if available. 5. Alternatively, download version 1.8.6+ from WordPress repository and manually update.
🔧 Temporary Workarounds
Disable Qubely Plugin
allTemporarily deactivate the vulnerable plugin until patched.
wp plugin deactivate qubely
Restrict AJAX Access
linuxBlock unauthenticated access to admin-ajax.php for Qubely endpoints via web application firewall or .htaccess.
# Add to .htaccess:
RewriteCond %{REQUEST_URI} ^/wp-admin/admin-ajax\.php$
RewriteCond %{QUERY_STRING} action=qubely_send_form_data
RewriteRule ^ - [F]
🧯 If You Can't Patch
- Implement rate limiting on admin-ajax.php endpoints
- Deploy web application firewall rules to block malicious POST requests to qubely_send_form_data
🔍 How to Verify
Check if Vulnerable:
Check WordPress admin panel > Plugins > Qubely version. If version is below 1.8.6, site is vulnerable.Check Version:
wp plugin get qubely --field=versionVerify Fix Applied:
Confirm Qubely plugin version is 1.8.6 or higher in WordPress admin.📡 Detection & Monitoring
Log Indicators:
- Multiple POST requests to /wp-admin/admin-ajax.php with 'action=qubely_send_form_data' from unauthenticated users
- Unusual email sending activity from WordPress site
Network Indicators:
- HTTP POST requests to admin-ajax.php with qubely_send_form_data parameter from external IPs
SIEM Query:
source="web_logs" AND uri="/wp-admin/admin-ajax.php" AND method="POST" AND query="*action=qubely_send_form_data*"