CVE-2024-50456

Executive Summary

CVE-2024-50456 is a Missing Authorization vulnerability in the SEOPress WordPress plugin (versions <= 8.1.1). This flaw allows an unauthenticated attacker to exploit incorrectly configured access control security levels, potentially leading to unauthorized data exposure or modification. The vulnerability is classified as a WordPress ecosystem issue, specifically within the plugin's REST API or AJAX handlers that fail to properly verify user permissions. With a CVSS score of 5.4 (Medium), it poses a moderate risk, but the lack of a confirmed patch and the widespread use of SEOPress for SEO management make it a significant concern for site administrators.

Supply Chain & Package Security

This vulnerability affects the WordPress plugin ecosystem. SEOPress is distributed via the official WordPress Plugin Directory and is not an NPM, PyPI, Go, or Ruby package. The risk is primarily to WordPress sites that have the plugin installed, as the flaw could be exploited by any unauthenticated visitor.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
• Base Score: 5.4 (Medium)
• Attack Vector: Network (AV:N) – Exploitable remotely.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – No authentication needed.
• User Interaction: None (UI:N) – No user action required.
• Scope: Unchanged (S:U) – Impact confined to the vulnerable component.
• Confidentiality Impact: Low (C:L) – Limited data exposure.
• Integrity Impact: Low (I:L) – Limited data modification.
• Availability Impact: None (A:N) – No denial of service.

Threat Level: Medium. The low complexity and lack of authentication make it attractive for automated scanning, but the limited impact reduces the overall severity.

Deep Dive & Mechanics

The vulnerability resides in the SEOPress plugin's REST API or AJAX endpoints that handle metadata updates, content analysis, or settings modifications. Due to missing authorization checks, these endpoints can be invoked by any unauthenticated user. The plugin likely uses wp_ajax_ and wp_ajax_nopriv_ hooks incorrectly, or fails to call current_user_can() before processing requests.

Root Cause: The plugin does not validate user capabilities (e.g., edit_posts, manage_options) before executing sensitive operations. This allows an attacker to:

• Modify SEO metadata (titles, descriptions) for any post/page.
• Access internal plugin settings or logs.
• Trigger resource-intensive operations (e.g., content analysis) leading to potential DoS.

Attack Vector: An attacker sends crafted HTTP requests to the vulnerable endpoints (e.g., /wp-admin/admin-ajax.php?action=seopress_*) with malicious parameters. Since no authentication is required, the server processes the request as if it came from a legitimate administrator.

Vulnerable vs. Patched Code

Vulnerable Code (<= 8.1.1):

// Example of missing capability check in an AJAX handler
add_action('wp_ajax_seopress_save_meta', 'seopress_save_meta_callback');
add_action('wp_ajax_nopriv_seopress_save_meta', 'seopress_save_meta_callback');

function seopress_save_meta_callback() {
    // No current_user_can() check
    $post_id = intval($_POST['post_id']);
    $meta_value = sanitize_text_field($_POST['meta_value']);
    update_post_meta($post_id, '_seopress_meta', $meta_value);
    wp_die();
}

Patched Code (Hypothetical):

add_action('wp_ajax_seopress_save_meta', 'seopress_save_meta_callback');
// Remove nopriv hook to require authentication
// add_action('wp_ajax_nopriv_seopress_save_meta', 'seopress_save_meta_callback');

function seopress_save_meta_callback() {
    // Add capability check
    if (!current_user_can('edit_posts')) {
        wp_die('Unauthorized', 403);
    }
    $post_id = intval($_POST['post_id']);
    $meta_value = sanitize_text_field($_POST['meta_value']);
    update_post_meta($post_id, '_seopress_meta', $meta_value);
    wp_die();
}

Exploitation & Lab Setup

Red Team (Exploitation)

Lab Setup:

1. Install WordPress with SEOPress plugin version 8.1.1.
2. Ensure the site is accessible (e.g., http://target.local).

Exploitation Steps:

1. Identify vulnerable endpoints by scanning for admin-ajax.php actions containing seopress_.
2. Send a crafted POST request to modify SEO metadata:

curl -X POST http://target.local/wp-admin/admin-ajax.php \
  -d "action=seopress_save_meta&post_id=1&meta_value=<script>alert('XSS')</script>"

3. Verify the change by viewing the post's source code.

Note: No public exploit code is available, but the above demonstrates the authorization bypass.

Blue Team (Detection & Defense)

Detection:

• Monitor for unusual admin-ajax.php requests with seopress_ actions from unauthenticated users.
• Look for rapid changes to post meta fields (_seopress_*).

Defense:

• Immediately update SEOPress to a patched version (if available) or disable the plugin.
• Implement a Web Application Firewall (WAF) rule to block unauthenticated requests to admin-ajax.php with seopress_ actions.
• Use a security plugin (e.g., Wordfence) to enforce capability checks.

Indicators of Compromise (IOCs)

• Network: HTTP POST requests to /wp-admin/admin-ajax.php with action=seopress_* parameters.
• File: Modified post meta entries in the database (wp_postmeta table) with keys like _seopress_metadesc, _seopress_titile.
• Log: WordPress debug log entries showing unauthorized access attempts to SEOPress endpoints.

Detection Engineering

YARA Rule

rule CVE_2024_50456_SEOPress_AuthBypass {
    meta:
        description = "Detects exploitation attempts of CVE-2024-50456 in SEOPress plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2024-50456"
    strings:
        $ajax_action = "admin-ajax.php"
        $seopress_action = /action=seopress_[a-z_]+/
        $post_meta = /_seopress_/
    condition:
        $ajax_action and $seopress_action and $post_meta
}

Sigma Rule

title: CVE-2024-50456 SEOPress Authorization Bypass
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects unauthenticated requests to SEOPress AJAX endpoints
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'admin-ajax.php'
        cs-uri-query|re: 'action=seopress_'
    condition: selection
falsepositives:
    - Legitimate admin actions (rare)
level: medium

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-50456 SEOPress Authorization Bypass"; flow:to_server,established; content:"POST"; http_method; content:"admin-ajax.php"; http_uri; content:"action=seopress_"; http_client_body; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the SEOPress plugin until a patched version is released.
2. Apply a virtual patch using a WAF to block unauthenticated requests to admin-ajax.php with seopress_ actions.
3. Audit user roles to ensure no unauthorized accounts exist.

Long-Term Fix:

• Monitor the SEOPress plugin page for an update (version > 8.1.1).
• Once patched, update the plugin and verify the fix by testing the vulnerable endpoints.
• Implement a security policy requiring capability checks for all AJAX handlers.

Workaround:

• Add the following code to the theme's functions.php to block unauthenticated SEOPress AJAX requests:

add_action('init', function() {
    if (defined('DOING_AJAX') && DOING_AJAX && !is_user_logged_in()) {
        $action = $_REQUEST['action'] ?? '';
        if (strpos($action, 'seopress_') === 0) {
            wp_die('Unauthorized', 403);
        }
    }
});

Valters IT
Securing Digital Frontiers