CVE-2025-4855: Support Board Auth Bypass Vulnerability

CVE-2025-4855 Overview

CVE-2025-4855 is a critical authorization bypass vulnerability affecting the Support Board plugin for WordPress. The vulnerability stems from the use of hardcoded default secrets in the sb_encryption() function, allowing unauthenticated attackers to bypass authorization controls and execute arbitrary AJAX actions through the sb_ajax_execute() function. This flaw enables unauthorized access, modification, and deletion of data on affected WordPress installations.

Critical Impact

Unauthenticated attackers can bypass authorization and execute arbitrary AJAX actions, potentially leading to complete compromise of WordPress sites using the Support Board plugin. This vulnerability can also be chained with CVE-2025-4828 for additional exploitation.

Affected Products

• Schiocco Support Board plugin for WordPress versions up to and including 3.8.0
• WordPress installations using the vulnerable Support Board plugin
• Self-hosted WordPress environments with the Support Board help desk and chat functionality

Discovery Timeline

• 2025-07-09 - CVE CVE-2025-4855 published to NVD
• 2025-07-14 - Last updated in NVD database

Technical Details for CVE-2025-4855

Vulnerability Analysis

The vulnerability resides in the Support Board plugin's encryption implementation. The sb_encryption() function uses hardcoded default secrets that are consistent across all installations of the plugin. Because these cryptographic secrets are embedded directly in the plugin's source code rather than being uniquely generated per installation, any attacker with knowledge of these values can forge valid authentication tokens.

The impact extends beyond simple data access. Once an attacker bypasses the authorization mechanism, they gain the ability to invoke any AJAX action defined within the sb_ajax_execute() function. This includes administrative operations that would normally require authenticated access with elevated privileges. The vulnerability is particularly dangerous as it can be leveraged to exploit additional vulnerabilities such as CVE-2025-4828 without any authentication.

Root Cause

The root cause is the use of hardcoded cryptographic secrets within the sb_encryption() function (CWE-639: Authorization Bypass Through User-Controlled Key). Instead of generating unique encryption keys during plugin installation or allowing administrators to configure custom secrets, the plugin ships with static default values. This design flaw means that all installations share identical encryption keys, effectively neutralizing the security controls that depend on them.

Attack Vector

The attack is network-based and can be executed by unauthenticated remote attackers. The exploitation process involves:

1. An attacker identifies a WordPress site running the vulnerable Support Board plugin
2. Using knowledge of the hardcoded encryption secrets, the attacker crafts malicious requests that appear legitimate to the plugin's authorization checks
3. The attacker sends these requests to the WordPress AJAX handler endpoint (/wp-admin/admin-ajax.php)
4. The sb_encryption() function validates the forged tokens as authentic due to the shared secrets
5. The sb_ajax_execute() function processes the attacker's chosen actions with full authorization

The vulnerability requires no user interaction and can be exploited directly over the network, making it highly accessible to attackers scanning for vulnerable WordPress installations.

Detection Methods for CVE-2025-4855

Indicators of Compromise

• Unusual AJAX requests to WordPress admin-ajax.php referencing Support Board actions from unknown IP addresses
• Unexpected modifications to Support Board data, configurations, or user accounts
• Authentication logs showing successful operations without corresponding legitimate user sessions
• Anomalous activity patterns in the Support Board plugin's functionality

Detection Strategies

• Monitor web server access logs for high volumes of requests to admin-ajax.php with Support Board-related action parameters
• Implement Web Application Firewall (WAF) rules to detect and block suspicious AJAX request patterns
• Review Support Board database tables for unauthorized modifications or new entries
• Deploy file integrity monitoring to detect unauthorized changes to plugin files

Monitoring Recommendations

• Enable detailed logging for all Support Board plugin operations and AJAX actions
• Configure alerts for failed or unusual authentication attempts related to the Support Board functionality
• Implement real-time monitoring of WordPress AJAX endpoints for anomalous request volumes
• Regularly audit Support Board user accounts and permissions for unauthorized changes

How to Mitigate CVE-2025-4855

Immediate Actions Required

• Update the Support Board plugin to a version newer than 3.8.0 that addresses this vulnerability
• If immediate update is not possible, temporarily disable the Support Board plugin until a patch can be applied
• Review audit logs for any signs of exploitation that may have occurred prior to patching
• Implement additional WAF rules to restrict access to Support Board AJAX endpoints

Patch Information

The vulnerability affects all versions of the Schiocco Support Board plugin up to and including version 3.8.0. Administrators should update to the latest available version that contains the security fix. The patch replaces the hardcoded encryption secrets with dynamically generated, installation-specific keys. Check the CodeCanyon Support Board product page for the latest version and update instructions. Additional technical details are available in the Wordfence Vulnerability Report.

Workarounds

• Disable the Support Board plugin entirely if updates cannot be applied immediately
• Implement IP-based access restrictions to the WordPress admin-ajax.php endpoint for Support Board actions
• Use a Web Application Firewall to filter and block suspicious requests to the affected AJAX endpoints
• Consider implementing additional authentication layers at the web server level for administrative functions

# Example: Restrict access to admin-ajax.php for Support Board actions (Apache .htaccess)
<Files "admin-ajax.php">
    <If "%{QUERY_STRING} =~ /support_board/">
        Require ip 192.168.1.0/24
    </If>
</Files>