CVE-2026-25456: FedEx Shipping Plugin Auth Bypass Flaw

CVE-2026-25456 Overview

A Missing Authorization vulnerability has been identified in the Aarsiv Groups "Automated FedEx live/manual rates with shipping labels" WordPress plugin (a2z-fedex-shipping). This vulnerability allows attackers to exploit incorrectly configured access control security levels, potentially leading to unauthorized access to sensitive shipping data and configuration settings.

The vulnerability stems from broken access control mechanisms within the plugin, enabling unauthenticated attackers to bypass authorization checks and access protected functionality. This is classified as CWE-862 (Missing Authorization), indicating that the affected component fails to perform proper authorization checks before granting access to restricted resources.

Critical Impact

Unauthenticated attackers can exploit missing authorization controls to access sensitive shipping configuration data, FedEx API credentials, and customer shipping information without proper authentication.

Affected Products

• Automated FedEx live/manual rates with shipping labels (a2z-fedex-shipping) versions through <= 5.1.8
• WordPress installations running the affected plugin versions
• WooCommerce stores utilizing the a2z-fedex-shipping plugin for shipping rate calculations

Discovery Timeline

• 2026-03-25 - CVE-2026-25456 published to NVD
• 2026-03-26 - Last updated in NVD database

Technical Details for CVE-2026-25456

Vulnerability Analysis

This vulnerability represents a Broken Access Control flaw where the a2z-fedex-shipping WordPress plugin fails to implement proper authorization checks on sensitive functionality. The plugin exposes administrative functions and data retrieval endpoints that can be accessed without verifying the user's permissions or authentication status.

WordPress plugins that handle shipping integrations typically manage sensitive data including API credentials, customer addresses, and shipping rates. When authorization controls are missing, this information becomes accessible to any user who can reach the vulnerable endpoints, regardless of their authentication status or role within the WordPress installation.

Root Cause

The root cause of this vulnerability is the absence of proper capability checks and nonce verification in the plugin's code. WordPress provides functions like current_user_can() and wp_verify_nonce() to ensure that only authorized users can access specific functionality. The a2z-fedex-shipping plugin versions through 5.1.8 fail to implement these security controls on certain AJAX handlers or administrative endpoints, allowing unauthorized access.

This type of vulnerability commonly occurs when developers expose functionality through WordPress AJAX actions without implementing the necessary authentication and authorization checks, or when direct access to plugin files is not properly restricted.

Attack Vector

The attack is network-based and requires no authentication or user interaction. An attacker can exploit this vulnerability by directly accessing the vulnerable endpoints, typically through crafted HTTP requests to the WordPress AJAX handler (admin-ajax.php) or directly to exposed plugin files.

The exploitation process typically involves:

1. Identifying the vulnerable AJAX actions or endpoints exposed by the plugin
2. Crafting HTTP requests to these endpoints without authentication headers or valid session cookies
3. Extracting sensitive configuration data, shipping information, or FedEx API credentials
4. Potentially modifying shipping rates or configuration settings if write access is also unprotected

For detailed technical information about this vulnerability, refer to the Patchstack WordPress Plugin Advisory.

Detection Methods for CVE-2026-25456

Indicators of Compromise

• Unusual HTTP requests to /wp-admin/admin-ajax.php with a2z-fedex-shipping related action parameters from unauthenticated sources
• Access attempts to plugin-specific endpoints from IP addresses not associated with legitimate administrators
• Anomalous patterns of requests targeting shipping configuration or FedEx API credential retrieval endpoints
• Unexpected changes to shipping rate configurations or FedEx integration settings

Detection Strategies

• Monitor web server access logs for requests to admin-ajax.php containing a2z-fedex-shipping action parameters without corresponding authentication
• Implement Web Application Firewall (WAF) rules to detect and block unauthorized access patterns targeting the plugin's endpoints
• Enable WordPress activity logging to track unauthorized attempts to access or modify shipping configurations
• Review database logs for unexpected queries to options tables containing FedEx API credentials

Monitoring Recommendations

• Deploy endpoint detection and response (EDR) solutions to monitor for post-exploitation activities on WordPress servers
• Implement file integrity monitoring on the wp-content/plugins/a2z-fedex-shipping/ directory to detect unauthorized modifications
• Configure alerts for unusual data exfiltration patterns from the WordPress database
• Monitor outbound connections from the web server for potential data theft attempts

How to Mitigate CVE-2026-25456

Immediate Actions Required

• Update the a2z-fedex-shipping plugin to the latest patched version immediately
• Review WordPress user accounts and access logs for any signs of unauthorized access or compromise
• Rotate FedEx API credentials if there is any indication of unauthorized access
• Implement a Web Application Firewall (WAF) to provide an additional layer of protection while patching

Patch Information

The vulnerability affects a2z-fedex-shipping plugin versions through 5.1.8. Site administrators should update to a version newer than 5.1.8 that addresses this missing authorization vulnerability. Check the official WordPress plugin repository or the Patchstack Advisory for the latest patched version information.

Workarounds

• Temporarily disable the a2z-fedex-shipping plugin if an immediate update is not possible
• Implement IP-based access restrictions to WordPress admin endpoints using server configuration
• Add a Web Application Firewall rule to block unauthenticated requests to a2z-fedex-shipping AJAX actions
• Consider using a security plugin like Wordfence or Sucuri to add additional access control layers

# Apache .htaccess configuration to restrict plugin access
# Add to WordPress root .htaccess file

<IfModule mod_rewrite.c>
    RewriteEngine On
    # Block direct access to a2z-fedex-shipping plugin files
    RewriteRule ^wp-content/plugins/a2z-fedex-shipping/.*\.php$ - [F,L]
</IfModule>

# Restrict admin-ajax.php to authenticated users only (use with caution)
# This may break legitimate AJAX functionality for unauthenticated users
<Files "admin-ajax.php">
    <RequireAll>
        Require all granted
    </RequireAll>
</Files>