CVE-2025-4177: Flynax Bridge Auth Bypass Vulnerability

CVE-2025-4177 Overview

CVE-2025-4177 is a broken access control vulnerability in the Flynax Bridge plugin for WordPress. The flaw exists in the deleteUser() function, which lacks a capability check in all versions up to and including 2.2.0. Unauthenticated attackers can invoke this function over the network to delete arbitrary WordPress user accounts. The issue is categorized under CWE-862: Missing Authorization.

Critical Impact
Remote, unauthenticated attackers can delete arbitrary user accounts on affected WordPress sites, disrupting site operations and enabling data loss.

Affected Products

Flynax Bridge plugin for WordPress, versions up to and including 2.2.0
WordPress sites integrating Flynax classifieds software through the bridge plugin
All WordPress installations with flynax-bridge active before the patched release

Discovery Timeline

2025-05-02 - CVE-2025-4177 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-4177

Vulnerability Analysis

The Flynax Bridge plugin exposes an API endpoint that routes requests to internal handlers, including the deleteUser() function defined in src/API.php. The function accepts a user identifier and removes the corresponding WordPress account. The plugin does not verify that the caller holds the delete_users capability or any equivalent administrative role before executing the deletion.

Because the endpoint is reachable without authentication, any remote actor can send a crafted request and trigger user removal. Attackers can enumerate user IDs and delete site administrators, subscribers, or contributors. The impact is limited to integrity loss, with no direct disclosure of confidential data or service outage beyond the affected accounts.

Root Cause

The root cause is a missing authorization check in the deleteUser() handler. The plugin developer did not call current_user_can() or validate a nonce before performing the destructive action. This omission maps directly to CWE-862 and follows a common WordPress plugin pattern where AJAX or REST handlers omit capability enforcement.

Attack Vector

Exploitation requires only network access to the target WordPress site. The attacker sends an HTTP request to the Flynax Bridge API endpoint with a target user identifier. No credentials, session cookies, or user interaction are required. Refer to the WordPress Plugin Source Code and the Wordfence Vulnerability Report for endpoint details.

No public proof-of-concept exploit code is available, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog.

Detection Methods for CVE-2025-4177

Indicators of Compromise

Unexpected deletion of WordPress user accounts recorded in the wp_users table or database audit logs
HTTP requests targeting Flynax Bridge API endpoints from unauthenticated sources
Missing administrator or editor accounts without a corresponding audit trail in WordPress activity logs

Detection Strategies

Monitor web server access logs for POST or GET requests to Flynax Bridge API routes originating from external IP addresses without prior authentication
Enable a WordPress activity logging plugin to track user deletion events and correlate them with source IP addresses
Alert on high volumes of requests to plugin endpoints under /wp-content/plugins/flynax-bridge/ or the plugin's registered REST routes

Monitoring Recommendations

Baseline the expected rate of user account changes and flag deviations for review
Forward WordPress and web server logs to a central SIEM for correlation across sites
Review the plugin's installed version against the patched release listed in the WordPress Changeset Update

How to Mitigate CVE-2025-4177

Immediate Actions Required

Update the Flynax Bridge plugin to the version released in changeset 3306501 or later
Audit the WordPress user list to confirm no unauthorized deletions have occurred
Restore missing accounts from database backups if evidence of exploitation is found
Restrict access to /wp-admin/ and plugin endpoints with IP allowlists where feasible

Patch Information

The vendor addressed the issue in the commit tracked at the WordPress Changeset Update. Administrators should upgrade to the first release that includes this fix. Verify the running version via the WordPress plugin dashboard after applying the update.

Workarounds

Deactivate and remove the Flynax Bridge plugin until the patched version is deployed
Deploy a Web Application Firewall (WAF) rule that blocks unauthenticated requests to the plugin's API endpoints
Enforce authentication at the reverse proxy or WAF layer for all administrative and plugin API paths

bash

# Example WAF rule concept to block unauthenticated Flynax Bridge API calls
# Deny requests to plugin endpoints when no valid WordPress auth cookie is present
SecRule REQUEST_URI "@contains /wp-content/plugins/flynax-bridge/" \
    "id:1004177,phase:1,deny,status:403,\
    chain,msg:'Block unauthenticated Flynax Bridge access - CVE-2025-4177'"
    SecRule &REQUEST_COOKIES:/wordpress_logged_in_/ "@eq 0"