CVE-2024-5857: Funnelforms Free Auth Bypass Vulnerability

CVE-2024-5857 Overview

CVE-2024-5857 affects the Funnelforms Free WordPress plugin, a drag-and-drop contact form and multi-step form builder. The vulnerability resides in the af2_handel_file_remove AJAX action, which lacks a capability check. Unauthenticated attackers can invoke the action and delete arbitrary media files from the WordPress installation. The flaw impacts all plugin versions up to and including 3.7.3.2. The weakness is categorized as missing authorization [CWE-862] and primarily affects data integrity on affected sites.

Critical Impact

Unauthenticated remote attackers can delete arbitrary media files from vulnerable WordPress sites, causing content loss and potential service disruption.

Affected Products

• Funnelforms Free plugin for WordPress, all versions through 3.7.3.2
• WordPress sites with the Interactive Contact Form and Multi Step Form Builder with Drag & Drop Editor installed
• Any WordPress environment where the vulnerable plugin remains active and unpatched

Discovery Timeline

• 2024-08-29 - CVE-2024-5857 published to NVD
• 2026-06-17 - Last updated in NVD database

Technical Details for CVE-2024-5857

Vulnerability Analysis

The Funnelforms Free plugin registers an AJAX handler named af2_handel_file_remove within its frontend request-processing code. The handler is responsible for removing uploaded files associated with form submissions. The function processes the request without verifying whether the caller holds the WordPress capability required to delete media. It also lacks a nonce check tied to a privileged user context. Because WordPress exposes AJAX endpoints via wp-admin/admin-ajax.php to both authenticated and unauthenticated requests when registered with the wp_ajax_nopriv_ prefix, any remote user can reach the vulnerable code path.

Root Cause

The root cause is a missing authorization check [CWE-862]. The handler should verify the caller’s capability using current_user_can() with an appropriate privilege such as delete_posts or upload_files, and validate a user-scoped nonce with check_ajax_referer(). Neither control is enforced before the file deletion operation executes. The vendor addressed the issue in changeset 3141470, published through the WordPress plugin repository.

Attack Vector

An attacker sends a crafted HTTP POST request to admin-ajax.php with the action parameter set to af2_handel_file_remove and a file identifier referencing a target media item. No authentication, user interaction, or elevated privileges are required. Successful requests remove the targeted media attachment, which can break pages, destroy marketing assets, or disrupt business operations that depend on hosted media.

The vulnerability manifests in the plugin’s frontend/frontend.php file. See the Wordfence Vulnerability Report and the WordPress Plugin Change Log for the technical fix details.

Detection Methods for CVE-2024-5857

Indicators of Compromise

• POST requests to /wp-admin/admin-ajax.php containing the parameter action=af2_handel_file_remove from unauthenticated sources
• Unexpected deletion events in the WordPress media library with no corresponding administrator activity
• Web server access logs showing anonymous clients repeatedly invoking the Funnelforms AJAX action with iterating file identifiers

Detection Strategies

• Inspect WordPress and web application firewall logs for the af2_handel_file_remove action string originating from non-admin sessions
• Correlate media file deletion timestamps with inbound HTTP traffic to admin-ajax.php to identify unauthorized removals
• Deploy file integrity monitoring on the wp-content/uploads directory to flag unexpected deletions

Monitoring Recommendations

• Alert on anonymous POST traffic to admin-ajax.php targeting plugin-specific actions, especially those containing file_remove or delete keywords
• Track installed plugin versions across WordPress estates and flag any Funnelforms Free instance at or below 3.7.3.2
• Enable WordPress audit logging to record media library changes and administrative actions for forensic review

How to Mitigate CVE-2024-5857

Immediate Actions Required

• Update the Funnelforms Free plugin to a version later than 3.7.3.2 that includes changeset 3141470
• If an update is not immediately possible, deactivate and remove the plugin until the patched release can be deployed
• Review the WordPress media library and restore any files deleted without authorization from backups

Patch Information

The vendor fixed the issue in the Funnelforms Free plugin via WordPress plugin repository changeset 3141470. The patch adds the missing authorization logic to the af2_handel_file_remove handler in frontend/frontend.php. Site operators should upgrade to the fixed release and verify the plugin version through the WordPress admin dashboard.

Workarounds

• Block requests to /wp-admin/admin-ajax.php where the action parameter equals af2_handel_file_remove at the web application firewall
• Restrict access to admin-ajax.php from untrusted networks where feasible using IP allowlisting or edge rules
• Maintain current, offline backups of the wp-content/uploads directory and the WordPress media database tables to support rapid recovery

# Example WAF rule (ModSecurity) to block the vulnerable AJAX action
SecRule REQUEST_URI "@endsWith /wp-admin/admin-ajax.php" \
    "chain,phase:2,deny,status:403,id:1005857,msg:'Block CVE-2024-5857 Funnelforms file removal'"
    SecRule ARGS:action "@streq af2_handel_file_remove" "t:none"