CVE-2025-3604: Flynax Bridge Privilege Escalation Flaw

CVE-2025-3604 Overview

CVE-2025-3604 is a critical privilege escalation vulnerability in the Flynax Bridge plugin for WordPress that enables unauthenticated attackers to take over any user account, including administrator accounts. The vulnerability exists because the plugin fails to properly validate a user's identity before allowing modifications to account details such as email addresses. An attacker can exploit this flaw to change an arbitrary user's email address, then leverage WordPress's password reset functionality to gain full access to the compromised account.

Critical Impact

Unauthenticated attackers can take over WordPress administrator accounts by changing email addresses without proper authorization, leading to complete site compromise.

Affected Products

• Flynax Bridge plugin for WordPress versions up to and including 2.2.0
• WordPress installations using vulnerable versions of flynax_bridge
• Sites integrating Flynax classified software with WordPress via this plugin

Discovery Timeline

• 2025-04-24 - CVE-2025-3604 published to NVD
• 2025-08-12 - Last updated in NVD database

Technical Details for CVE-2025-3604

Vulnerability Analysis

This vulnerability falls under CWE-862 (Missing Authorization), representing a critical broken access control flaw in the Flynax Bridge plugin. The plugin provides integration between WordPress and Flynax classified ads software, handling user synchronization between the two platforms. The vulnerable functionality resides in the user profile update mechanism, which accepts requests to modify user account details without verifying whether the requester is authorized to make such changes.

The attack is particularly dangerous because it requires no authentication, meaning any remote attacker can target WordPress sites running the vulnerable plugin. Once an attacker changes an administrator's email address to one they control, they can initiate a password reset through WordPress's standard recovery mechanism, receiving the reset link at their own email address and gaining complete administrative access to the WordPress installation.

Root Cause

The root cause is a missing authorization check in the plugin's request handling code. When processing user profile update requests, the plugin updates user details including email addresses without first validating that the requesting party has permission to modify the target user's account. This allows unauthenticated requests to modify any user's information simply by referencing their user ID or username.

Attack Vector

The attack is network-based and requires no authentication or user interaction. An attacker can remotely send crafted HTTP requests to the vulnerable endpoint in the request.php file. The attack flow proceeds as follows: first, the attacker identifies a target WordPress site running the Flynax Bridge plugin; second, they send a malicious request to update an administrator's email address to an attacker-controlled address; third, they initiate a password reset for the targeted administrator account; finally, they receive the password reset email at their controlled address and gain administrative access.

The vulnerability is documented in the WordPress Plugin Request File and detailed analysis is available in the Wordfence Vulnerability Report.

Detection Methods for CVE-2025-3604

Indicators of Compromise

• Unexpected changes to WordPress user email addresses, particularly administrator accounts
• Password reset requests initiated for accounts where the legitimate user did not request them
• Suspicious HTTP POST requests to /wp-content/plugins/flynax-bridge/request.php containing user modification parameters
• Admin account access from unfamiliar IP addresses or geographic locations following email changes

Detection Strategies

• Monitor WordPress audit logs for unauthorized email address modifications on user accounts
• Implement Web Application Firewall (WAF) rules to detect and block suspicious requests to the Flynax Bridge plugin endpoints
• Configure alerts for password reset emails sent to newly changed email addresses
• Review HTTP access logs for unusual patterns of requests targeting plugin files

Monitoring Recommendations

• Enable WordPress user activity logging to track all profile modifications with timestamps and source IPs
• Set up email notifications when administrator account details are changed
• Implement rate limiting on requests to plugin endpoints to slow down automated exploitation attempts
• Deploy endpoint detection solutions to monitor for post-exploitation activities following account takeover

How to Mitigate CVE-2025-3604

Immediate Actions Required

• Update the Flynax Bridge plugin to a version newer than 2.2.0 if a patched version is available
• If no patch is available, immediately deactivate and remove the Flynax Bridge plugin from affected WordPress installations
• Audit all WordPress user accounts for unauthorized email address changes
• Force password resets for all administrator accounts as a precautionary measure
• Review WordPress access logs for signs of exploitation

Patch Information

Organizations should check for updated versions of the Flynax Bridge plugin through the WordPress plugin repository or contact the Flynax vendor directly. Until a patch is confirmed and deployed, the plugin should be considered a critical security risk. Additional details and updates may be available through the Wordfence Vulnerability Report.

Workarounds

• Disable the Flynax Bridge plugin until a security patch is available and applied
• Implement WAF rules to block unauthenticated requests to the plugin's request.php endpoint
• Restrict access to the plugin directory via .htaccess or web server configuration rules
• Use WordPress security plugins to enforce additional authorization checks on user modification actions

# Block access to vulnerable plugin file via .htaccess
# Add to WordPress root .htaccess or wp-content/plugins/flynax-bridge/.htaccess

<Files "request.php">
    Order Deny,Allow
    Deny from all
    # Allow only from trusted IP addresses if integration is required
    # Allow from 192.168.1.100
</Files>