CVE-2025-31923

Executive Summary

CVE-2025-31923 is a Missing Authorization vulnerability in the CSS3 Accordions for WordPress plugin by QuanticaLabs, affecting versions up to and including 3.0. This flaw allows authenticated attackers (with low privileges) to exploit incorrectly configured access control security levels, potentially leading to unauthorized data access or modification. The vulnerability is classified as a WordPress ecosystem issue and does not involve Apache or Nginx server software.

The vulnerability has a CVSS score of 5.4 (Medium) and an EPSS score of 0.0%, indicating low exploitation likelihood in the wild. No public proof-of-concept (PoC) or exploit code is currently available. The patch status remains UNKNOWN/UNPATCHED, meaning users must apply manual mitigations or disable the plugin until a fix is released.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. Users should verify the integrity of their plugin files and monitor for updates from QuanticaLabs. No known supply chain compromise has been reported.

CVSS Breakdown & Threat Level

• CVSS Score: 5.4 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: Low
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: None

Threat Level: Medium. The vulnerability requires authentication but allows low-privilege users to bypass access controls, potentially leading to unauthorized actions.

Deep Dive & Mechanics

The vulnerability resides in the CSS3 Accordions for WordPress plugin, specifically in its access control implementation. The plugin fails to properly validate user permissions when processing certain AJAX requests or shortcode handlers, allowing authenticated users with minimal privileges (e.g., subscribers) to perform actions intended for higher-privilege roles (e.g., editors or administrators).

Root Cause: The plugin uses current_user_can() checks incorrectly or omits them entirely in some functions, leading to missing authorization. This is a classic CWE-862: Missing Authorization flaw.

Attack Vector: An attacker with a valid WordPress account (e.g., subscriber) can craft HTTP requests to trigger unauthorized actions, such as modifying accordion settings, accessing private data, or escalating privileges.

Impact: Successful exploitation could lead to:

• Unauthorized modification of plugin settings.
• Exposure of sensitive data stored in accordion content.
• Potential privilege escalation if combined with other vulnerabilities.

Vulnerable vs. Patched Code

Since no official patch is available, the following is a hypothetical comparison based on the vulnerability type.

Vulnerable Code (Example):

function css3_accordions_save_settings() {
    // Missing authorization check
    update_option('css3_accordions_settings', $_POST['settings']);
    wp_die();
}
add_action('wp_ajax_css3_accordions_save', 'css3_accordions_save_settings');

Patched Code (Hypothetical):

function css3_accordions_save_settings() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized');
    }
    update_option('css3_accordions_settings', $_POST['settings']);
    wp_die();
}
add_action('wp_ajax_css3_accordions_save', 'css3_accordions_save_settings');

The patched version adds a capability check (manage_options) to ensure only administrators can modify settings.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• A WordPress instance with CSS3 Accordions plugin version <= 3.0.
• A valid low-privilege user account (e.g., subscriber).

Exploitation Steps:

1. Log in as a low-privilege user.
2. Identify vulnerable AJAX endpoints by analyzing plugin JavaScript files (e.g., admin-ajax.php actions).
3. Craft a request to exploit missing authorization. Example using curl:

   curl -X POST 'http://target/wp-admin/admin-ajax.php' \
   -d 'action=css3_accordions_save&settings[malicious]=value' \
   --cookie 'wordpress_logged_in_xxx=session_cookie'
   

4. Verify unauthorized changes (e.g., modified plugin settings).

Note: No public exploit code is available; this is a conceptual demonstration.

Blue Team (Defensive)

Detection & Response:

• Monitor for unusual AJAX requests from low-privilege users to sensitive plugin endpoints.
• Implement Web Application Firewall (WAF) rules to block requests to admin-ajax.php with unexpected actions.
• Use file integrity monitoring to detect unauthorized changes to plugin files or options.

Honeypot Setup:

• Deploy a decoy WordPress instance with the vulnerable plugin to capture attacker behavior.

Indicators of Compromise (IOCs)

• File Hashes (SHA256): (Example – replace with actual plugin file hashes)
  • css3-accordions.php: a1b2c3d4e5f6...
  • includes/class-css3-accordions.php: f6e5d4c3b2a1...
• Network Patterns:
  • POST requests to /wp-admin/admin-ajax.php with action=css3_accordions_* from low-privilege users.
• Log Entries:
  • WordPress debug log entries showing unauthorized access attempts.
• Database Changes:
  • Unexpected modifications to wp_options table entries prefixed with css3_accordions_.

Detection Engineering

YARA Rule

rule CVE_2025_31923_CSS3_Accordions_Missing_Auth {
    meta:
        description = "Detects missing authorization in CSS3 Accordions for WordPress plugin"
        author = "Valters IT"
        date = "2025-04-01"
        hash = "a1b2c3d4e5f6..."
    strings:
        $vuln_func = "current_user_can" nocase
        $ajax_action = "wp_ajax_css3_accordions" nocase
    condition:
        #vuln_func < 2 and #ajax_action > 0
}

Sigma Rule

title: CVE-2025-31923 - Missing Authorization in CSS3 Accordions
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects exploitation attempts of missing authorization in CSS3 Accordions plugin
author: Valters IT
date: 2025/04/01
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'admin-ajax.php'
        cs-uri-query|contains: 'action=css3_accordions_'
    condition: selection
falsepositives:
    - Legitimate admin actions
level: medium

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-31923 - CSS3 Accordions Missing Authorization Exploit";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"admin-ajax.php"; http_uri;
    content:"action=css3_accordions_"; http_client_body;
    classtype:attempted-admin;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until an official patch is released.
2. Restrict user roles – Remove unnecessary low-privilege accounts.
3. Apply virtual patching using a WAF to block suspicious AJAX requests.

Long-term Fix:

• Monitor the plugin's official page for updates.
• If no patch is forthcoming, consider replacing the plugin with an alternative.

Workaround:

• Add custom code to functions.php to enforce capability checks:

  add_action('wp_ajax_css3_accordions_save', function() {
      if (!current_user_can('manage_options')) {
          wp_die('Unauthorized');
      }
  }, 1);
  

Valters IT
Securing Digital Frontiers