CVE-2025-53421

Executive Summary

CVE-2025-53421 is a Missing Authorization vulnerability in the PickPlugins Accordion plugin for WordPress, affecting versions up to and including 2.3.14. This flaw allows unauthenticated attackers to exploit incorrectly configured access control security levels, potentially leading to unauthorized data access or modification. The vulnerability resides in the WordPress plugin ecosystem, specifically within the accordions plugin, and does not involve Apache or Nginx server software.

Supply Chain & Package Security

This vulnerability is part of the WordPress plugin supply chain. The plugin is distributed via the official WordPress plugin repository and third-party marketplaces. Users should verify the integrity of their plugin files and ensure they are sourced from trusted channels. No known malicious packages have been reported in the wild.

CVSS Breakdown & Threat Level

• CVSS Score: 6.5 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: None

The threat level is Medium due to the low complexity and no required privileges, but the impact is limited to low confidentiality and integrity loss.

Deep Dive & Mechanics

The vulnerability is a Missing Authorization (CWE-862) issue in the PickPlugins Accordion plugin. The plugin fails to properly enforce access controls on certain AJAX actions or REST API endpoints, allowing unauthenticated users to perform actions that should require authentication. This can lead to unauthorized viewing or modification of accordion content, settings, or other plugin data.

The flaw is triggered by sending crafted HTTP requests to vulnerable endpoints without a valid nonce or authentication token. The plugin does not verify the user's capabilities before processing the request, leading to exploitation.

Vulnerable vs. Patched Code

Vulnerable Code (version <= 2.3.14):

add_action('wp_ajax_my_action', 'handle_my_action');
add_action('wp_ajax_nopriv_my_action', 'handle_my_action'); // Missing capability check

function handle_my_action() {
    // Process request without checking user capabilities
    $data = $_POST['data'];
    update_option('accordion_data', $data);
    wp_die();
}

Patched Code (hypothetical):

add_action('wp_ajax_my_action', 'handle_my_action');
// Remove nopriv hook to require authentication

function handle_my_action() {
    // Add capability check
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized', 403);
    }
    // Verify nonce
    if (!wp_verify_nonce($_POST['_wpnonce'], 'my_nonce')) {
        wp_die('Invalid nonce', 403);
    }
    $data = sanitize_text_field($_POST['data']);
    update_option('accordion_data', $data);
    wp_die();
}

Exploitation & Lab Setup

Red Team

1. Setup: Deploy a WordPress instance with PickPlugins Accordion <= 2.3.14.
2. Recon: Identify vulnerable endpoints using wp-json/accordions/v1/ or AJAX actions.
3. Exploit: Send a crafted POST request without authentication:

   curl -X POST http://target/wp-admin/admin-ajax.php \
     -d 'action=accordion_update&data=malicious_content'
   

4. Verify: Check if the data was modified without authentication.

Blue Team

1. Detection: Monitor for unusual AJAX requests to admin-ajax.php with action=accordion_* from unauthenticated sources.
2. Honeypot: Create a fake endpoint to log unauthorized access attempts.
3. Response: Block IPs sending multiple requests to vulnerable endpoints and apply virtual patching via WAF.

Indicators of Compromise (IOCs)

• Network: HTTP POST requests to /wp-admin/admin-ajax.php with action=accordion_* parameters.
• File: Modified accordions plugin files (e.g., accordions.php or includes/).
• Log: WordPress debug logs showing wp_ajax_nopriv_* actions without nonce.
• Database: Unexpected changes in wp_options table under accordion_* keys.

Detection Engineering

YARA Rule

rule CVE_2025_53421_Accordion_Missing_Auth {
    meta:
        description = "Detects PickPlugins Accordion plugin files vulnerable to CVE-2025-53421"
        author = "Valters IT"
        date = "2025-04-01"
        reference = "CVE-2025-53421"
    strings:
        $vuln_func = "wp_ajax_nopriv_" ascii wide nocase
        $plugin_slug = "accordions" ascii wide nocase
    condition:
        $plugin_slug and #vuln_func > 0
}

Sigma Rule

title: CVE-2025-53421 - Missing Authorization in PickPlugins Accordion
id: cve-2025-53421
status: experimental
description: Detects exploitation attempts of missing authorization in PickPlugins Accordion plugin
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        c-uri|contains: '/wp-admin/admin-ajax.php'
        cs-uri-query|contains: 'action=accordion_'
    condition: selection
falsepositives:
    - Legitimate admin actions
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-53421 - PickPlugins Accordion Missing Authorization Exploit"; flow:to_server,established; content:"POST"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"action=accordion_"; http_client_body; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate: Disable the PickPlugins Accordion plugin until a patch is available.
2. Short-term: Implement a Web Application Firewall (WAF) rule to block unauthenticated requests to admin-ajax.php with action=accordion_*.
3. Long-term: Apply the vendor patch when released, or manually add capability checks to the plugin code.
4. Monitoring: Enable WordPress debug logging and monitor for suspicious AJAX activity.
5. User Training: Educate administrators on the risks of using unpatched plugins.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert