CVE-2025-62021

Executive Summary

CVE-2025-62021 is a Missing Authorization vulnerability (CWE-862) in the Acknowledgify WordPress plugin by Made Neat, affecting versions up to and including 1.1.3. This flaw allows unauthenticated attackers to access or modify protected resources due to insufficient permission checks on certain AJAX actions or REST endpoints. The CVSS score is 4.3 (Medium), with a low EPSS probability (0.0%), indicating limited active exploitation at this time. No public exploit code or patch is available, making this a high-priority issue for WordPress site administrators using the plugin.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. Since no patch exists, the supply chain risk is elevated—users must either implement a virtual patch (e.g., via WAF) or remove the plugin entirely. The plugin’s codebase is closed-source, preventing community-driven fixes.

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) – Unauthenticated access.
• User Interaction (UI): None (N) – No user action needed.
• Scope (S): Unchanged (U) – Exploit stays within the plugin.
• Confidentiality (C): Low (L) – Limited data exposure.
• Integrity (I): None (N) – No data modification.
• Availability (A): None (N) – No denial of service.

Threat Level: Medium. While the CVSS is low, the lack of a patch and the plugin’s widespread use in WordPress ecosystems elevate the risk for unmanaged installations.

Deep Dive & Mechanics

The vulnerability stems from missing current_user_can() or wp_verify_nonce() checks in the plugin’s AJAX handlers. WordPress plugins often expose admin-ajax.php endpoints for frontend/backend interactions. In Acknowledgify, certain actions (e.g., fetching acknowledgments, updating settings) are registered without verifying the user’s capabilities. An attacker can craft a POST request to /wp-admin/admin-ajax.php with the appropriate action parameter to trigger these functions.

Root Cause: The plugin’s developer failed to implement authorization checks in functions hooked to wp_ajax_* and wp_ajax_nopriv_* actions. The nopriv hook allows unauthenticated access, but even authenticated users with low privileges (e.g., subscribers) could escalate access.

Attack Flow:

1. Attacker identifies the vulnerable AJAX action (e.g., acknowledgify_get_data).
2. Sends a crafted HTTP POST request to https://target.com/wp-admin/admin-ajax.php with action=acknowledgify_get_data.
3. The server processes the request without verifying the user’s role, returning sensitive data (e.g., user lists, acknowledgment logs).

Vulnerable vs. Patched Code

Since no patch is available, we can only infer the vulnerable pattern. A typical fix would involve adding capability checks:

Vulnerable Code (Hypothetical):

add_action('wp_ajax_nopriv_acknowledgify_get_data', 'acknowledgify_get_data');
function acknowledgify_get_data() {
    // No permission check
    $data = get_option('acknowledgify_data');
    wp_send_json_success($data);
}

Patched Code (Hypothetical):

add_action('wp_ajax_acknowledgify_get_data', 'acknowledgify_get_data');
function acknowledgify_get_data() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized', 403);
    }
    $data = get_option('acknowledgify_data');
    wp_send_json_success($data);
}

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites: Target WordPress site with Acknowledgify <= 1.1.3 installed and active.

Step 1: Reconnaissance Identify the AJAX action by inspecting the plugin’s JavaScript or using a tool like Burp Suite to intercept requests.

Step 2: Craft Exploit Use curl to send an unauthenticated request:

curl -X POST https://target.com/wp-admin/admin-ajax.php \
  -d "action=acknowledgify_get_data" \
  -H "Content-Type: application/x-www-form-urlencoded"

Step 3: Verify If successful, the response will contain JSON data (e.g., acknowledgment logs, user info). If a 403 or empty response is returned, the action may require a nonce or specific parameters.

Lab Setup:

• Install WordPress locally (e.g., via Docker).
• Install Acknowledgify plugin version 1.1.3.
• Use a tool like Postman or Burp Suite to send requests.

Blue Team (Detection & Response)

• Monitor admin-ajax.php requests for unknown action parameters.
• Look for repeated requests from the same IP without a valid session cookie.
• Check for anomalous data retrieval patterns (e.g., bulk export of acknowledgment data).

Indicators of Compromise (IOCs)

• Network: HTTP POST requests to /wp-admin/admin-ajax.php with action=acknowledgify_* parameters from unauthenticated sources.
• Logs: WordPress debug log entries showing acknowledgify_get_data or similar function calls without a valid user context.
• File: Unexpected presence of acknowledgify plugin files in /wp-content/plugins/acknowledgify/.
• Behavior: Unauthorized access to acknowledgment data or settings changes.

Detection Engineering

YARA Rule

rule CVE_2025_62021_Acknowledgify_Missing_Auth {
    meta:
        description = "Detects exploitation attempts for CVE-2025-62021 in Acknowledgify plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-62021"
    strings:
        $ajax_action = "acknowledgify_" ascii wide nocase
        $admin_ajax = "admin-ajax.php" ascii wide nocase
    condition:
        $ajax_action and $admin_ajax
}

Sigma Rule

title: CVE-2025-62021 - Missing Authorization in Acknowledgify Plugin
id: 8a7b3c2d-1e5f-4a6b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects unauthenticated AJAX requests targeting Acknowledgify plugin
author: Valters IT
date: 2025/04/10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: '/wp-admin/admin-ajax.php'
        cs-uri-query|contains: 'action=acknowledgify_'
    condition: selection
falsepositives:
    - Legitimate plugin AJAX calls from authenticated users
level: medium

Suricata Rule

alert http any any -> any any (
    msg:"CVE-2025-62021 - Acknowledgify Missing Authorization Exploit";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/wp-admin/admin-ajax.php"; http_uri;
    content:"action=acknowledgify_"; http_client_body;
    classtype:attempted-recon;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the Plugin: Deactivate and delete the Acknowledgify plugin until a patch is released.
2. Virtual Patching: Use a Web Application Firewall (WAF) to block requests to admin-ajax.php with action=acknowledgify_* from unauthenticated sources.
3. Access Controls: Restrict access to /wp-admin/ directory via .htaccess or IP whitelisting.

Long-Term Fix:

• Monitor the plugin’s official page for updates. If no patch is released within 30 days, consider migrating to an alternative plugin.
• Implement a Content Security Policy (CSP) to limit script execution.

Valters IT Signature This report was generated by Valters IT DevSecOps AI. For questions, contact security@valters-it.com.