CVE-2024-4157
📋 TL;DR
This vulnerability allows authenticated WordPress users with contributor-level access or higher to perform PHP object injection via deserialization of untrusted input in the Fluent Forms plugin. Attackers can potentially delete files, steal data, or execute arbitrary code if a suitable POP chain exists from other plugins/themes. The vulnerability affects all WordPress sites using Fluent Forms plugin versions up to 5.1.15.
💻 Affected Systems
- Fluent Forms - Contact Form, Quiz, Survey, and Drag & Drop WP Form Builder
📦 What is this software?
Contact Form by Fluentforms
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete site compromise, data theft, and server takeover if combined with a suitable POP chain.
Likely Case
Arbitrary file deletion or sensitive data exposure through existing POP chains in commonly installed plugins.
If Mitigated
Limited impact if proper access controls are enforced and no suitable POP chains exist on the system.
🎯 Exploit Status
Exploitation requires authenticated access and a suitable POP chain. The CVE-2024-2771 bypass makes exploitation easier.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 5.1.16
Vendor Advisory: https://plugins.trac.wordpress.org/changeset/3081740/fluentform
Restart Required: No
Instructions:
1. Log into WordPress admin panel. 2. Navigate to Plugins → Installed Plugins. 3. Find 'Fluent Forms' and click 'Update Now'. 4. Verify version is 5.1.16 or higher.
🔧 Temporary Workarounds
Remove vulnerable plugin
allTemporarily disable or remove the Fluent Forms plugin until patched
wp plugin deactivate fluentform
wp plugin delete fluentform
Restrict user permissions
allRemove 'View Form' and 'Manage Form' permissions from all non-administrator users
🧯 If You Can't Patch
- Disable the Fluent Forms plugin immediately
- Implement strict access controls and monitor for suspicious activity from contributor-level users
🔍 How to Verify
Check if Vulnerable:
Check WordPress admin panel → Plugins → Installed Plugins → Fluent Forms version. If version is 5.1.15 or lower, you are vulnerable.Check Version:
wp plugin get fluentform --field=versionVerify Fix Applied:
Verify Fluent Forms plugin version is 5.1.16 or higher in WordPress admin panel.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /wp-admin/admin-ajax.php with 'action=fluentform' parameters
- Unexpected file deletion or modification events
- Suspicious PHP deserialization errors in logs
Network Indicators:
- HTTP requests containing serialized PHP objects in POST data
- Unusual outbound connections from WordPress server
SIEM Query:
source="wordpress.logs" AND ("fluentform" OR "extractDynamicValues") AND ("deserialization" OR "unserialize")🔗 References
- https://plugins.trac.wordpress.org/changeset/3081740/fluentform
- https://www.wordfence.com/threat-intel/vulnerabilities/id/8def156a-f2f2-4640-a1c9-c21c74e1f308?source=cve
- https://plugins.trac.wordpress.org/changeset/3081740/fluentform
- https://www.wordfence.com/threat-intel/vulnerabilities/id/8def156a-f2f2-4640-a1c9-c21c74e1f308?source=cve
