CVE-2024-2771: Fluentforms Privilege Escalation Flaw

CVE-2024-2771 Overview

CVE-2024-2771 is a privilege escalation vulnerability affecting the Fluent Forms plugin for WordPress. The vulnerability exists due to a missing capability check on the /wp-json/fluentform/v1/managers REST API endpoint, allowing unauthenticated attackers to manipulate user permissions and gain unauthorized access to the plugin's administrative features.

Critical Impact

Unauthenticated attackers can grant arbitrary users Fluent Form management permissions, gaining full access to all plugin settings and features. Additionally, attackers can delete existing manager accounts, potentially disrupting site operations and security controls.

Affected Products

• Fluent Forms for WordPress versions up to and including 5.1.16
• Contact Form Plugin by Fluent Forms for Quiz, Survey, and Drag & Drop WP Form Builder
• WordPress installations using vulnerable Fluent Forms plugin versions

Discovery Timeline

• 2024-05-18 - CVE-2024-2771 published to NVD
• 2025-02-06 - Last updated in NVD database

Technical Details for CVE-2024-2771

Vulnerability Analysis

This vulnerability is classified as CWE-862 (Missing Authorization), a broken access control flaw that occurs when an application fails to verify whether a user has the required permissions to perform a specific action. In the context of WordPress plugins, REST API endpoints should implement proper capability checks to ensure only authorized users can access sensitive functionality.

The vulnerable endpoint at /wp-json/fluentform/v1/managers handles the management of user roles and permissions within the Fluent Forms plugin. Without proper authentication and authorization verification, the endpoint accepts requests from any visitor, including unauthenticated users.

The exploitation potential for this vulnerability is significant, with an EPSS probability of 27.09% placing it in the 96th percentile of all vulnerabilities—indicating a high likelihood of exploitation in the wild.

Root Cause

The root cause of CVE-2024-2771 lies in the RoleManagerPolicy.php file within the Fluent Forms plugin. The REST API endpoint handler failed to implement the necessary WordPress capability checks (such as current_user_can()) before processing requests that modify manager permissions. This oversight allowed any HTTP request to the endpoint to be processed regardless of the requester's authentication status or authorization level.

Attack Vector

The attack is conducted remotely over the network without requiring any prior authentication or user interaction. An attacker can exploit this vulnerability by:

1. Identifying a WordPress site running a vulnerable version of Fluent Forms
2. Crafting malicious HTTP requests to the /wp-json/fluentform/v1/managers REST API endpoint
3. Sending requests to either grant administrative Fluent Form permissions to attacker-controlled accounts or delete existing manager accounts
4. Using the elevated permissions to access plugin settings, form submissions (potentially containing sensitive data), and modify form configurations

The attack does not require valid credentials, making it particularly dangerous for internet-facing WordPress installations.

Detection Methods for CVE-2024-2771

Indicators of Compromise

• Unexpected changes to Fluent Forms manager accounts or permissions
• New user accounts with Fluent Forms administrative privileges that were not created by legitimate administrators
• Missing or deleted Fluent Forms manager accounts without corresponding administrative actions
• Unusual REST API requests to /wp-json/fluentform/v1/managers from external IP addresses

Detection Strategies

• Monitor WordPress access logs for unauthenticated requests to the /wp-json/fluentform/v1/managers endpoint
• Implement Web Application Firewall (WAF) rules to detect and block suspicious REST API calls targeting Fluent Forms endpoints
• Review WordPress user tables and Fluent Forms permissions for unauthorized modifications
• Configure alerting for any changes to plugin manager roles outside of normal administrative windows

Monitoring Recommendations

• Enable detailed logging for all WordPress REST API endpoints, particularly those handling user permissions
• Implement real-time monitoring for Fluent Forms permission changes using WordPress hooks and security plugins
• Regularly audit Fluent Forms manager accounts and compare against approved administrator lists
• Deploy endpoint detection solutions to monitor for post-exploitation activities on WordPress servers

How to Mitigate CVE-2024-2771

Immediate Actions Required

• Update Fluent Forms plugin immediately to version 5.1.17 or later
• Audit all current Fluent Forms manager accounts and remove any unauthorized users
• Review WordPress access logs for evidence of exploitation attempts
• Temporarily disable the Fluent Forms plugin if immediate patching is not possible
• Consider restricting access to WordPress REST API endpoints at the web server level until patching is complete

Patch Information

The Fluent Forms development team has addressed this vulnerability in version 5.1.17. The fix implements proper capability checks in the RoleManagerPolicy.php file to ensure only authenticated users with appropriate permissions can access the managers endpoint. The patch can be reviewed at the WordPress Plugin Changeset.

For additional technical details about this vulnerability, refer to the Wordfence Vulnerability Report.

Workarounds

• Restrict access to WordPress REST API endpoints using web server configuration rules (e.g., Apache .htaccess or Nginx location blocks)
• Implement a Web Application Firewall (WAF) rule to block requests to /wp-json/fluentform/v1/managers from unauthenticated sources
• Use WordPress security plugins to enforce additional authentication requirements on REST API endpoints
• Temporarily disable the Fluent Forms plugin entirely if the business function allows, until patching can be completed

# Nginx configuration to restrict Fluent Forms REST API access
# Add to server block configuration
location ~* /wp-json/fluentform/v1/managers {
    # Allow only authenticated admin requests from trusted IPs
    allow 192.168.1.0/24;  # Replace with your admin IP range
    deny all;
}