CVE-2025-67994

Executive Summary

CVE-2025-67994 is a Missing Authorization vulnerability in the YayCurrency WordPress plugin by YayCommerce. This flaw allows an unauthenticated attacker to exploit incorrectly configured access control security levels, potentially leading to unauthorized modification of currency settings or data. The vulnerability affects all versions of YayCurrency up to and including version 3.3. As of this report, no official patch has been released, and the vendor's status is marked as UNKNOWN/UNPATCHED.

The vulnerability is classified as High Severity with a CVSS score of 7.5, primarily due to the lack of required privileges and the potential for integrity impact. The EPSS score is 0.0%, indicating low exploitation likelihood in the wild, but the absence of a patch makes it a significant risk for unmaintained installations.

Supply Chain & Package Security

This vulnerability resides in a WordPress plugin distributed via the official WordPress plugin repository. Organizations using YayCurrency should verify their version and consider disabling the plugin until a patch is available. The plugin is not distributed via NPM, PyPI, Go, or Ruby ecosystems.

CVSS Breakdown & Threat Level

• CVSS Score: 7.5 (High)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
• Attack Vector (AV): Network – The vulnerability can be exploited remotely.
• Attack Complexity (AC): Low – No special conditions are required.
• Privileges Required (PR): None – No authentication needed.
• User Interaction (UI): None – No user action required.
• Scope (S): Unchanged – The exploit does not affect other components.
• Confidentiality (C): None – No data disclosure.
• Integrity (I): High – Unauthorized modification of data is possible.
• Availability (A): None – No denial of service.

Threat Level: High. The lack of required privileges and the potential for data manipulation make this a critical risk for affected WordPress sites.

Deep Dive & Mechanics

The vulnerability stems from a Missing Authorization check in the YayCurrency plugin's REST API endpoints or AJAX handlers. The plugin likely exposes functions that modify currency settings, exchange rates, or user preferences without verifying that the requesting user has the appropriate capabilities (e.g., manage_options or edit_posts).

Root Cause: The plugin fails to call current_user_can() or similar authorization checks before executing sensitive operations. This allows any unauthenticated user to send crafted HTTP requests to manipulate currency data.

Attack Vector: An attacker can send a POST request to a vulnerable endpoint (e.g., /wp-admin/admin-ajax.php with specific action parameters) to modify currency settings, potentially leading to:

• Changing exchange rates to defraud users.
• Disabling currency conversion features.
• Injecting malicious data into the database.

Impact: Successful exploitation can compromise the integrity of the e-commerce platform, leading to financial discrepancies or loss of customer trust.

Vulnerable vs. Patched Code

Since no patch is available, the following is a hypothetical comparison based on common WordPress authorization patterns.

Vulnerable Code (Example):

add_action('wp_ajax_nopriv_yaycurrency_update_rate', 'yaycurrency_update_rate');
function yaycurrency_update_rate() {
    // No capability check
    $rate = $_POST['rate'];
    update_option('yaycurrency_exchange_rate', $rate);
    wp_die();
}

Patched Code (Hypothetical):

add_action('wp_ajax_nopriv_yaycurrency_update_rate', 'yaycurrency_update_rate');
function yaycurrency_update_rate() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized', 403);
    }
    $rate = sanitize_text_field($_POST['rate']);
    update_option('yaycurrency_exchange_rate', $rate);
    wp_die();
}

The patched version adds a capability check using current_user_can('manage_options') and sanitizes input.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• A WordPress site with YayCurrency plugin version <= 3.3.
• Network access to the target.

Exploitation Steps:

1. Identify the vulnerable endpoint by analyzing the plugin's AJAX actions (e.g., yaycurrency_update_rate).
2. Send a crafted POST request using curl:

   curl -X POST http://target.com/wp-admin/admin-ajax.php \
     -d "action=yaycurrency_update_rate&rate=1.5"
   

3. Verify the change by checking the currency display on the site.

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

Blue Team (Defensive)

Detection:

• Monitor for unusual POST requests to /wp-admin/admin-ajax.php with parameters containing yaycurrency actions.
• Look for rapid changes in currency settings or exchange rates.

Mitigation:

• Disable the YayCurrency plugin until a patch is released.
• Implement a Web Application Firewall (WAF) rule to block requests to vulnerable endpoints from unauthenticated users.
• Use WordPress security plugins to enforce capability checks.

Indicators of Compromise (IOCs)

• Network IOCs:
  • POST requests to /wp-admin/admin-ajax.php with action=yaycurrency_* parameters from unauthenticated sources.
  • Unusual exchange rate values in HTTP responses.
• File IOCs:
  • Modified wp_options table entries for yaycurrency_exchange_rate.
• Log IOCs:
  • Repeated 403 errors from AJAX handlers (if patched) or successful unauthorized requests.

Detection Engineering

YARA Rule

rule Detect_YayCurrency_Exploit {
    meta:
        description = "Detects exploitation attempts against CVE-2025-67994"
        author = "Valters IT"
        date = "2025-04-10"
    strings:
        $ajax_action = "yaycurrency" nocase
        $post_param = "action=" nocase
    condition:
        $ajax_action and $post_param
}

Sigma Rule

title: YayCurrency Missing Authorization Exploit
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects unauthorized POST requests to YayCurrency AJAX endpoints
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: POST
        cs-uri-stem: '/wp-admin/admin-ajax.php'
        cs-uri-query|contains: 'action=yaycurrency'
    condition: selection
falsepositives:
    - Legitimate admin actions (if patched)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-67994 YayCurrency Missing Authorization Exploit"; flow:to_server; http.method; content:"POST"; http.uri; content:"/wp-admin/admin-ajax.php"; http.client_body; content:"action=yaycurrency"; nocase; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the YayCurrency plugin if not critical to operations.
2. Monitor logs for unauthorized AJAX requests.
3. Apply virtual patching via WAF rules to block unauthenticated access to yaycurrency actions.

Long-term Fix:

• Wait for an official patch from YayCommerce.
• Consider replacing the plugin with an alternative that has proper authorization checks.

Workaround:

• Add a custom code snippet to the theme's functions.php to enforce capability checks:

  add_action('init', function() {
      if (isset($_POST['action']) && strpos($_POST['action'], 'yaycurrency') !== false) {
          if (!current_user_can('manage_options')) {
              wp_die('Unauthorized', 403);
          }
      }
  });
  

Valters IT
Securing Digital Frontiers