CVE-2025-47681

Executive Summary

CVE-2025-47681 is a Cross-Site Request Forgery (CSRF) vulnerability in the WordPress plugin "Web Accessibility with Max Access" by Ability, Inc. This plugin is designed to add an accessibility toolbar to WordPress sites. The vulnerability affects all versions up to and including 2.0.9. A successful CSRF attack can force an authenticated administrator to perform unintended actions, such as changing plugin settings or deactivating the plugin, without their consent. The CVSS score is 4.3 (Medium), and no public proof-of-concept or patch is currently available. The EPSS score is 0.0%, indicating a very low probability of exploitation in the wild at this time.

Supply Chain & Package Security

This vulnerability is specific to the WordPress plugin ecosystem. The plugin is distributed via the WordPress Plugin Directory and is not an NPM, PyPI, Go, or Ruby package. Administrators should verify the integrity of the plugin files by checking checksums provided by the WordPress Plugin Directory or the vendor.

CVSS Breakdown & Threat Level

• CVSS Score: 4.3 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required (victim must click a link or visit a malicious page)
• Scope: Unchanged
• Confidentiality Impact: None
• Integrity Impact: Low (attacker can modify plugin settings or perform actions on behalf of admin)
• Availability Impact: None

Threat Level: Medium. While the impact is limited to integrity, the attack requires no privileges and low complexity. The lack of a patch increases the risk for unmaintained sites.

Deep Dive & Mechanics

The vulnerability lies in the absence of CSRF nonces or tokens in the plugin's administrative actions. When an authenticated WordPress administrator accesses the plugin's settings page or performs actions (e.g., saving settings, enabling/disabling features), the plugin does not verify that the request originated from the legitimate admin session. This allows an attacker to craft a malicious link or HTML form that, when clicked by an admin, triggers an unintended action.

Attack Flow:

1. Attacker identifies a target WordPress site running the vulnerable plugin.
2. Attacker crafts a malicious HTML page or email containing a CSRF payload (e.g., a form that auto-submits to the plugin's settings endpoint).
3. Attacker lures an authenticated admin to visit the malicious page.
4. The admin's browser sends a forged request to the WordPress site, including the admin's session cookies.
5. The plugin processes the request without validating the origin, leading to unauthorized changes.

Root Cause: Missing CSRF protection (nonce) in all administrative functions of the plugin.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code is the current state of the plugin (<= 2.0.9). A patched version would include nonce verification.

Vulnerable Code Example (PHP):

// In admin-settings.php
function save_settings() {
    // No nonce check
    update_option('max_access_settings', $_POST['settings']);
    wp_redirect(admin_url('admin.php?page=max-access-settings'));
}

Patched Code Example (Hypothetical):

// In admin-settings.php
function save_settings() {
    if (!isset($_POST['_wpnonce']) || !wp_verify_nonce($_POST['_wpnonce'], 'max_access_save_settings')) {
        wp_die('CSRF validation failed.');
    }
    update_option('max_access_settings', $_POST['settings']);
    wp_redirect(admin_url('admin.php?page=max-access-settings'));
}

Exploitation & Lab Setup

Red Team (Attack Simulation)

Prerequisites:

• Target WordPress site with plugin version <= 2.0.9.
• An authenticated admin session (victim).

Exploit Payload (HTML):

<html>
<body>
<form action="http://target-site.com/wp-admin/admin-post.php?action=max_access_save_settings" method="POST">
    <input type="hidden" name="settings[enable_toolbar]" value="0" />
    <input type="submit" value="Click me" />
</form>
<script>document.forms[0].submit();</script>
</body>
</html>

Steps:

1. Host the HTML file on an attacker-controlled server.
2. Send the link to the victim admin via email or social engineering.
3. When the admin visits the page, the form auto-submits, disabling the toolbar.

Blue Team (Defense & Detection)

Detection:

• Monitor for unusual POST requests to /wp-admin/admin-post.php with action parameters related to the plugin (e.g., max_access_save_settings).
• Check for missing Referer headers or unexpected Referer values in admin requests.

Prevention:

• Implement a Web Application Firewall (WAF) rule to block requests to plugin admin actions without a valid nonce.
• Educate administrators about phishing and CSRF risks.

Indicators of Compromise (IOCs)

• Network: HTTP POST requests to /wp-admin/admin-post.php with action=max_access_save_settings and no _wpnonce parameter.
• Logs: WordPress debug log entries showing wp_die calls for nonce failures (if patched).
• File: Modified plugin settings in the wp_options table (option name: max_access_settings).

Detection Engineering

YARA Rule

rule CVE_2025_47681_CSRF_Plugin {
    meta:
        description = "Detects vulnerable Web Accessibility with Max Access plugin files"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-47681"
    strings:
        $func1 = "function save_settings" nocase
        $func2 = "update_option('max_access_settings'" nocase
        $no_nonce = "wp_verify_nonce" nocase
    condition:
        $func1 and $func2 and not $no_nonce
}

Sigma Rule

title: CVE-2025-47681 CSRF Exploitation Attempt
id: 8a7b3c2d-1e5f-4a6b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects CSRF attempts against Web Accessibility with Max Access plugin
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'action=max_access_save_settings'
        cs-referer|re: '^(?!https?:\/\/target-site\.com).*$'
    condition: selection
falsepositives:
    - Legitimate admin actions from the same site
level: medium

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-47681 CSRF Attempt - Web Accessibility with Max Access";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/wp-admin/admin-post.php"; http_uri;
    content:"action=max_access_save_settings"; http_client_body;
    pcre:"/Referer:[^\r\n]*?(?!target-site\.com)/i";
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin if not essential, until a patch is released.
2. Implement a WAF rule to block requests to plugin admin actions without a valid nonce.
3. Restrict admin access to trusted IPs and enforce strong authentication.

Long-term Fix:

• The vendor (Ability, Inc) must release a patched version that includes CSRF nonces in all admin actions. Until then, consider replacing the plugin with an alternative.

Workaround:

• Add a custom function to the theme's functions.php to add nonce checks:

add_action('admin_post_max_access_save_settings', function() {
    if (!wp_verify_nonce($_REQUEST['_wpnonce'], 'max_access_save_settings')) {
        wp_die('CSRF detected.');
    }
}, 1);

Valters IT
Securing Digital Frontiers