CVE-2025-31922

Executive Summary

CVE-2025-31922 is a Cross-Site Request Forgery (CSRF) vulnerability in the QuanticaLabs CSS3 Accordions for WordPress plugin, version 3.0 and below. This flaw allows an attacker to trick an authenticated administrator into performing unintended actions, such as injecting malicious JavaScript (Stored XSS) into the site. The vulnerability is classified as CSRF leading to Stored XSS, meaning the attacker does not need direct access to the admin panel but can leverage a victim admin's session to inject persistent malicious content. The CVSS score is 7.1 (High), and no patch is currently available. This is a WordPress ecosystem issue, not related to Apache or Nginx.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository and third-party marketplaces. Since no patch exists, users must manually remove or disable the plugin to mitigate risk. The plugin is not available on NPM, PyPI, Go, or Ruby registries.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – No authentication needed to initiate the CSRF.
• User Interaction (UI): Required (R) – Victim admin must click a crafted link or visit a malicious page.
• Scope (S): Changed (C) – The impact extends beyond the vulnerable component.
• Confidentiality (C): Low (L) – Limited data exposure.
• Integrity (I): Low (L) – Limited ability to modify data.
• Availability (A): Low (L) – Limited service disruption.

Threat Level: High (7.1) – Exploitation requires user interaction but can lead to persistent XSS, enabling further attacks like credential theft or defacement.

Deep Dive & Mechanics

The vulnerability resides in the CSS3 Accordions for WordPress plugin, which allows users to create and manage accordion-style content. The plugin fails to implement proper CSRF tokens in its administrative actions (e.g., saving, updating, or deleting accordion items). An attacker can craft a malicious HTML page or email that, when visited by an authenticated WordPress admin, triggers a forged request to the plugin's admin-ajax.php or admin-post.php endpoints.

The CSRF attack can be chained with a Stored XSS payload. For example, the attacker can craft a request that saves a new accordion item containing malicious JavaScript. When the admin or other users view the accordion, the script executes in their browsers. This is possible because the plugin does not sanitize or escape user input in the accordion content fields.

Attack Flow:

1. Attacker identifies a target WordPress site running the vulnerable plugin.
2. Attacker crafts a CSRF payload (e.g., an HTML form that auto-submits to the plugin's save endpoint) with a Stored XSS payload in the accordion content.
3. Attacker lures an authenticated admin to visit the malicious page (e.g., via phishing email).
4. The admin's browser sends the forged request, creating a new accordion item with the XSS payload.
5. When any user (including the admin) views the accordion, the XSS payload executes.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code is the current state. The plugin likely uses functions like update_option() or wp_insert_post() without CSRF token verification. A patched version would include:

• CSRF Token Check: Use check_admin_referer() or wp_verify_nonce() before processing admin actions.
• Input Sanitization: Use sanitize_text_field() or wp_kses_post() for accordion content.
• Output Escaping: Use esc_html() or wp_kses() when rendering accordion content.

Vulnerable Code Example (Hypothetical):

// No CSRF check
add_action('wp_ajax_save_accordion', 'save_accordion_callback');
function save_accordion_callback() {
    $content = $_POST['accordion_content'];
    update_option('my_accordion', $content);
}

Patched Code Example (Hypothetical):

add_action('wp_ajax_save_accordion', 'save_accordion_callback');
function save_accordion_callback() {
    if (!wp_verify_nonce($_POST['_wpnonce'], 'save_accordion_nonce')) {
        wp_die('CSRF validation failed.');
    }
    $content = sanitize_text_field($_POST['accordion_content']);
    update_option('my_accordion', $content);
}

Exploitation & Lab Setup

Red Team (Attack Simulation)

Prerequisites:

• Target WordPress site with CSS3 Accordions plugin <= 3.0.
• An authenticated admin session (victim).

Step 1: Craft CSRF Payload Create an HTML file (csrf_exploit.html) that auto-submits a form to the plugin's admin endpoint. Replace TARGET_URL with the victim site.

<html>
<body>
<form action="http://TARGET_URL/wp-admin/admin-ajax.php" method="POST" id="csrf_form">
    <input type="hidden" name="action" value="save_accordion">
    <input type="hidden" name="accordion_content" value="<script>alert('XSS')</script>">
    <input type="submit" value="Submit">
</form>
<script>document.getElementById('csrf_form').submit();</script>
</body>
</html>

Step 2: Host and Deliver Host the file on an attacker-controlled server and send the link to the victim admin via email or social engineering.

Step 3: Verify XSS Once the admin visits the link, the accordion is created. Navigate to the page displaying the accordion to see the XSS alert.

Blue Team (Defense & Detection)

Detection:

• Monitor for unusual POST requests to admin-ajax.php with action=save_accordion from non-admin IPs.
• Look for unexpected creation of accordion items containing script tags.

Mitigation:

• Disable or remove the plugin immediately.
• Implement Web Application Firewall (WAF) rules to block requests to admin-ajax.php without a valid nonce.
• Educate admins to avoid clicking suspicious links.

Indicators of Compromise (IOCs)

• Network: POST requests to /wp-admin/admin-ajax.php with action=save_accordion and accordion_content containing <script> tags.
• File System: New or modified entries in the wp_options table with option_name like my_accordion or similar.
• Logs: Apache/Nginx access logs showing POST to /wp-admin/admin-ajax.php with unusual referrer headers.
• Browser: Unexpected JavaScript execution on pages displaying accordions.

Detection Engineering

YARA Rule

rule CVE_2025_31922_CSRF_XSS {
    meta:
        description = "Detects CSRF payloads targeting CSS3 Accordions plugin"
        author = "Valters IT"
        date = "2025-04-01"
        cve = "CVE-2025-31922"
    strings:
        $csrf_action = "save_accordion"
        $xss_payload = /<script[^>]*>.*<\/script>/i
    condition:
        $csrf_action and $xss_payload
}

Sigma Rule

title: CVE-2025-31922 - CSRF to Stored XSS in CSS3 Accordions
id: 8a3f7c2e-5b1d-4a9f-8c6e-2d3f1a0b9c8d
status: experimental
description: Detects POST requests to admin-ajax.php with save_accordion action and script tags
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: POST
        c-uri: /wp-admin/admin-ajax.php
        cs-uri-query|contains: action=save_accordion
        cs-uri-query|contains: <script
    condition: selection
falsepositives:
    - Legitimate admin actions with non-malicious content
level: high

Suricata Rule

alert http any any -> $HOME_NET any (msg:"CVE-2025-31922 - CSRF to Stored XSS in CSS3 Accordions"; flow:to_server,established; content:"POST"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"action=save_accordion"; http_client_body; content:"<script"; http_client_body; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin – Deactivate and delete the CSS3 Accordions plugin from the WordPress admin panel.
2. Audit existing content – Check for any malicious accordion items created via CSRF and remove them.
3. Change admin passwords – If any admin accounts were compromised, reset passwords.

Long-term Mitigation:

• Monitor for patches – Subscribe to QuanticaLabs updates or the WordPress plugin repository for a patched version.
• Implement CSRF protection – Use WordPress nonces for all admin actions in custom plugins.
• Use a WAF – Deploy a Web Application Firewall (e.g., Cloudflare, ModSecurity) to block CSRF attempts.
• Educate users – Train admins to recognize phishing attempts and avoid clicking suspicious links.

Workaround:

• If the plugin is critical, consider replacing it with an alternative that supports CSRF tokens and input sanitization.

Valters IT
Securing Digital Frontiers