CVE-2025-24606

Executive Summary

CVE-2025-24606 is a Missing Authorization vulnerability in the BoldGrid Client Invoicing by Sprout Invoices WordPress plugin, affecting versions up to and including 20.8.1. This flaw allows an authenticated attacker with low privileges (e.g., a subscriber) to exploit incorrectly configured access control security levels, potentially leading to unauthorized viewing, modification, or deletion of invoice data. The vulnerability has a CVSS score of 6.4 (Medium), indicating a moderate risk due to the requirement for authentication but the potential for significant data exposure.

Supply Chain & Package Security

This vulnerability resides in a WordPress plugin distributed via the official WordPress plugin repository. Users who installed the plugin via the WordPress dashboard or through automated deployment tools (e.g., Composer, WP-CLI) are affected. No known supply chain compromise has been reported, but the lack of a vendor patch increases the risk of exploitation in the wild.

CVSS Breakdown & Threat Level

• CVSS Score: 6.4 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): Low (L) – Attacker needs a valid WordPress user account (e.g., subscriber).
• User Interaction (UI): None (N) – No victim action needed.
• Scope (S): Unchanged (U) – Vulnerability does not affect other components.
• Confidentiality (C): Low (L) – Limited data exposure (invoice details).
• Integrity (I): Low (L) – Limited data modification possible.
• Availability (A): Low (L) – Limited service disruption possible.

Threat Level: Medium. While authentication is required, the low complexity and network attack vector make this a viable target for attackers who have already compromised a low-privilege account.

Deep Dive & Mechanics

The vulnerability stems from improper authorization checks in the Sprout Invoices plugin's REST API endpoints or AJAX handlers. The plugin fails to verify that the current user has the necessary capabilities (e.g., edit_invoices, manage_options) before allowing access to sensitive operations such as:

• Viewing invoice lists and details.
• Creating, editing, or deleting invoices.
• Accessing client billing information.

The missing authorization check likely occurs in functions that handle requests to endpoints like /wp-json/sprout-invoices/v1/invoices or similar custom routes. An attacker with a subscriber-level account can craft HTTP requests to these endpoints, bypassing the intended access controls.

Root Cause: The plugin uses current_user_can() checks inconsistently or relies on nonces without verifying user roles, allowing low-privilege users to perform actions reserved for administrators or shop managers.

Vulnerable vs. Patched Code

Since no official patch is available, the following is a hypothetical comparison based on common fixes for such vulnerabilities.

Vulnerable Code (hypothetical):

// In a REST API callback
function get_invoices( $request ) {
    // Missing capability check
    $invoices = Invoice::get_all();
    return rest_ensure_response( $invoices );
}

Patched Code (hypothetical):

function get_invoices( $request ) {
    if ( ! current_user_can( 'edit_invoices' ) ) {
        return new WP_Error( 'rest_forbidden', 'You do not have permission to view invoices.', array( 'status' => 403 ) );
    }
    $invoices = Invoice::get_all();
    return rest_ensure_response( $invoices );
}

The patch adds a current_user_can() check before processing the request, ensuring only users with the edit_invoices capability can access the data.

Exploitation & Lab Setup

Red Team

Prerequisites:

• A WordPress site with Sprout Invoices plugin version <= 20.8.1.
• A valid low-privilege user account (e.g., subscriber).

Exploitation Steps:

1. Log in as the low-privilege user and obtain a WordPress nonce or cookie.
2. Craft a GET request to the vulnerable endpoint:

   GET /wp-json/sprout-invoices/v1/invoices HTTP/1.1
   Host: target-site.com
   Cookie: wordpress_logged_in_<hash>=<session_cookie>
   

3. If the endpoint returns invoice data, the vulnerability is confirmed.
4. For more impact, attempt to create or modify invoices via POST requests:

   POST /wp-json/sprout-invoices/v1/invoices HTTP/1.1
   Host: target-site.com
   Content-Type: application/json
   Cookie: wordpress_logged_in_<hash>=<session_cookie>
   
   {
     "client_id": 1,
     "amount": 1000,
     "status": "paid"
   }
   

Expected Outcome: Unauthorized access to invoice data or creation of fraudulent invoices.

Blue Team

Detection Steps:

1. Monitor WordPress REST API logs for unusual access patterns from low-privilege users.
2. Look for requests to /wp-json/sprout-invoices/v1/ endpoints from users with roles like subscriber or contributor.
3. Check for sudden creation of invoices by unexpected users.
4. Use the detection rules below to identify exploitation attempts.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP requests to /wp-json/sprout-invoices/v1/invoices from authenticated sessions with low-privilege roles.
  • Unusual POST/PUT/DELETE requests to invoice endpoints from non-admin users.
• File IOCs:
  • Modified or newly created invoice records in the WordPress database (wp_posts with post type sprout-invoice).
• Log IOCs:
  • WordPress debug log entries showing WP_Error for rest_forbidden (if a partial patch is applied).
  • Web server access logs showing repeated requests to the vulnerable endpoint.

Detection Engineering

YARA Rule

rule CVE_2025_24606_Sprout_Invoices_Missing_Auth {
    meta:
        description = "Detects exploitation attempts of CVE-2025-24606 in Sprout Invoices plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2025-24606"
    strings:
        $endpoint = "/wp-json/sprout-invoices/v1/invoices"
        $user_role = "subscriber"
    condition:
        $endpoint and $user_role
}

Sigma Rule

title: CVE-2025-24606 - Sprout Invoices Missing Authorization
id: 8a4b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects unauthorized access to Sprout Invoices REST API endpoints
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access_combined
detection:
    selection:
        cs-uri-query|contains: "/wp-json/sprout-invoices/v1/invoices"
        cs-method: 
            - "GET"
            - "POST"
            - "PUT"
            - "DELETE"
    condition: selection
falsepositives:
    - Legitimate admin actions
level: medium

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-24606 - Sprout Invoices Missing Authorization Attempt"; flow:to_server,established; content:"/wp-json/sprout-invoices/v1/invoices"; http_uri; nocase; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until an official patch is released.
2. Implement a Web Application Firewall (WAF) rule to block requests to /wp-json/sprout-invoices/v1/ from non-admin users.
3. Review user roles and remove any unnecessary low-privilege accounts.

Long-term Fix:

• Monitor the BoldGrid plugin repository for a patched version (expected > 20.8.1).
• Apply the patch manually by adding current_user_can() checks to all REST API callbacks in the plugin's code.

Workaround:

• Use a WordPress security plugin (e.g., Wordfence, Sucuri) to restrict access to the plugin's endpoints based on user role.

Valters IT