CVE-2025-62751

Executive Summary

CVE-2025-62751 is a Missing Authorization vulnerability in the Extendthemes Vireo WordPress theme, affecting all versions up to and including 1.0.24. This flaw allows an unauthenticated attacker to exploit incorrectly configured access control security levels, potentially leading to unauthorized data access or privilege escalation. The vulnerability resides within the WordPress ecosystem and is not related to the underlying web server (Apache/Nginx). With a CVSS score of 4.3 (Medium), the risk is moderate but elevated due to the lack of a known patch and the widespread use of WordPress themes. No public proof-of-concept (PoC) or exploit code has been released, and the EPSS score is 0.0%, indicating low exploitation likelihood in the wild.

Supply Chain & Package Security

This vulnerability affects a WordPress theme distributed via the Extendthemes marketplace and potentially through WordPress theme repositories. As a WordPress component, it is part of a larger supply chain where theme updates are managed through the WordPress dashboard or manual uploads. The absence of a patch means that users must rely on alternative mitigation strategies, such as disabling the theme or applying custom access controls. Organizations using Vireo should treat this as a supply chain risk and monitor for updates from Extendthemes.

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.
• User Interaction (UI): None (N) – No user action required.
• Scope (S): Unchanged (U) – Vulnerability does not affect other components.
• Confidentiality (C): Low (L) – Limited data exposure possible.
• Integrity (I): None (N) – No data modification.
• Availability (A): None (N) – No denial of service.

Threat Level: Medium. The vulnerability is easy to exploit but has limited impact. However, the lack of a patch increases the risk for organizations that cannot immediately mitigate.

Deep Dive & Mechanics

The vulnerability stems from Missing Authorization (CWE-862) in the Vireo theme’s access control implementation. Specifically, certain REST API endpoints or AJAX actions within the theme do not properly verify user permissions before executing sensitive operations. This allows an unauthenticated attacker to:

• Access private theme settings or user data.
• Trigger actions intended for administrators, such as modifying theme options or retrieving non-public information.

The flaw is likely located in the theme’s functions.php or custom plugin files that register WordPress REST API routes without proper capability checks. For example, a route like /wp-json/vireo/v1/settings might return sensitive configuration data without requiring a valid nonce or user capability.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code remains in all versions <= 1.0.24. A hypothetical fix would involve adding capability checks to all REST API endpoints and AJAX handlers.

Vulnerable Code Example (PHP):

add_action('rest_api_init', function () {
    register_rest_route('vireo/v1', '/settings', array(
        'methods' => 'GET',
        'callback' => 'vireo_get_settings',
        // Missing 'permission_callback' => '__return_true' or proper capability
    ));
});

function vireo_get_settings() {
    return get_option('vireo_theme_settings');
}

Patched Code Example (PHP):

add_action('rest_api_init', function () {
    register_rest_route('vireo/v1', '/settings', array(
        'methods' => 'GET',
        'callback' => 'vireo_get_settings',
        'permission_callback' => function () {
            return current_user_can('manage_options');
        }
    ));
});

function vireo_get_settings() {
    return get_option('vireo_theme_settings');
}

Exploitation & Lab Setup

Red Team

Objective: Exploit the missing authorization to extract sensitive theme settings.

Prerequisites:

• A WordPress site running Vireo theme version <= 1.0.24.
• Network access to the target.

Steps:

1. Identify the vulnerable endpoint by analyzing the theme’s JavaScript or PHP files for REST API routes without permission_callback.
2. Send a direct GET request to the endpoint:

   curl -X GET https://target.com/wp-json/vireo/v1/settings
   

3. If successful, the response will contain sensitive data such as API keys, database credentials, or user lists.

Note: No public exploit code is available; this is a theoretical approach based on the vulnerability description.

Blue Team

Objective: Detect and block exploitation attempts.

Detection:

• Monitor for unusual requests to /wp-json/vireo/v1/* endpoints from unauthenticated sources.
• Use WAF rules to block access to unknown REST API routes.

Mitigation:

• Disable the Vireo theme if not in use.
• Apply a custom plugin that adds capability checks to all theme endpoints.
• Restrict access to the WordPress REST API via .htaccess or server configuration.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests to /wp-json/vireo/v1/settings or similar paths without authentication.
  • Unusual GET/POST requests to AJAX actions prefixed with vireo_.
• File IOCs:
  • Presence of the Vireo theme directory: /wp-content/themes/vireo/.
  • Modified functions.php or custom plugin files that remove permission checks.
• Log IOCs:
  • WordPress debug logs showing rest_no_route errors for Vireo endpoints.
  • Web server access logs with 200 responses to /wp-json/vireo/v1/* from unknown IPs.

Detection Engineering

YARA Rule

rule Detect_Vireo_Missing_Auth {
    meta:
        description = "Detects vulnerable Vireo theme files with missing permission callbacks"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-62751"
    strings:
        $rest_route = /register_rest_route\s*\(\s*['\"]vireo\/v1['\"]/
        $no_permission = /'permission_callback'\s*=>\s*__return_true/
        $missing_callback = /register_rest_route\s*\([^)]+\)\s*;\s*(?!.*permission_callback)/
    condition:
        $rest_route and ($no_permission or $missing_callback)
}

Sigma Rule

title: Unauthenticated Access to Vireo REST API Endpoints
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects attempts to exploit CVE-2025-62751 by accessing Vireo theme REST API without authentication
author: Valters IT
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: 'GET'
        cs-uri-stem|startswith: '/wp-json/vireo/v1/'
        sc-status: 200
    condition: selection
falsepositives:
    - Legitimate admin requests if authentication is bypassed via other means
level: medium

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-62751 - Unauthenticated Vireo REST API Access"; flow:to_server; http.method; content:"GET"; http.uri; content:"/wp-json/vireo/v1/"; startswith; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the Vireo theme if it is not critical to operations. Switch to a default WordPress theme (e.g., Twenty Twenty-Four).
2. Apply a virtual patch using a Web Application Firewall (WAF) to block requests to /wp-json/vireo/v1/* from unauthenticated users.
3. Monitor for updates from Extendthemes. If a patch becomes available, apply it immediately.

Long-Term Measures:

• Implement a WordPress security plugin (e.g., Wordfence, Sucuri) that enforces capability checks on all REST API endpoints.
• Conduct a code review of all custom themes and plugins for missing authorization checks.
• Adopt a least-privilege model for WordPress user roles and capabilities.

Workaround:

• Add the following code to a custom plugin or theme’s functions.php to block unauthenticated access to Vireo endpoints:

  add_filter('rest_authentication_errors', function($result) {
      if (strpos($_SERVER['REQUEST_URI'], '/wp-json/vireo/v1/') !== false && !is_user_logged_in()) {
          return new WP_Error('rest_not_logged_in', 'You must be logged in.', array('status' => 401));
      }
      return $result;
  });
  

Valters IT
Securing Digital Frontiers