CVE-2025-49857

Executive Summary

CVE-2025-49857 is a Missing Authorization vulnerability in the myCred WordPress plugin, developed by Saad Iqbal. This flaw allows an unauthenticated attacker to exploit incorrectly configured access control security levels, potentially leading to unauthorized actions or data exposure. The vulnerability affects all versions of myCred from n/a through 2.9.4.2. As of this report, no official patch has been released, and the vendor's patch status is unknown. The CVSS score is 4.3 (Medium), indicating a moderate risk primarily due to low attack complexity and no required privileges, but with limited impact on confidentiality and integrity.

Supply Chain & Package Security

This vulnerability resides in the WordPress plugin ecosystem, specifically within the myCred plugin. WordPress plugins are distributed via the official WordPress Plugin Directory and third-party marketplaces. Users are advised to monitor the plugin's page for updates and consider disabling the plugin if no patch is available. The lack of a patch increases supply chain risk, as site administrators may unknowingly run vulnerable code.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
• Base Score: 4.3 (Medium)
• 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) – Impact confined to the vulnerable component.
• Confidentiality (C): None (N) – No data disclosure.
• Integrity (I): Low (L) – Limited ability to modify data.
• Availability (A): None (N) – No denial of service.

Threat Level: Medium. The vulnerability is easy to exploit remotely without authentication, but the impact is limited to low integrity compromise. Attackers may manipulate certain settings or data within the myCred plugin.

Deep Dive & Mechanics

The myCred plugin is a gamification and points management system for WordPress. The missing authorization vulnerability (CWE-862) occurs when the plugin fails to properly enforce access controls on certain AJAX actions or REST API endpoints. Specifically, functions that handle user points, badges, or ranks may be callable by unauthenticated users, allowing them to modify their own or others' points without proper permission checks.

Root Cause: The plugin likely uses wp_ajax_* hooks without corresponding wp_ajax_nopriv_* checks, or it fails to validate user capabilities (e.g., current_user_can()) before executing sensitive operations. This allows any visitor to trigger actions intended only for authenticated users with specific roles.

Attack Scenario: An attacker sends a crafted HTTP request to a vulnerable endpoint (e.g., /wp-admin/admin-ajax.php?action=mycred_add_points) with parameters to increase their points balance. Since no authorization check is performed, the request succeeds, granting the attacker unearned rewards.

Vulnerable vs. Patched Code

Since no patch is available, we can only infer the vulnerable code pattern. A typical vulnerable snippet might look like:

// Vulnerable: No capability check
add_action('wp_ajax_mycred_add_points', 'mycred_add_points_callback');
function mycred_add_points_callback() {
    $user_id = $_POST['user_id'];
    $points = $_POST['points'];
    mycred_update_user_meta($user_id, 'mycred_points', $points);
    wp_die();
}

A patched version would include:

// Patched: Check user capabilities
add_action('wp_ajax_mycred_add_points', 'mycred_add_points_callback');
function mycred_add_points_callback() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized', 403);
    }
    $user_id = $_POST['user_id'];
    $points = $_POST['points'];
    mycred_update_user_meta($user_id, 'mycred_points', $points);
    wp_die();
}

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• A WordPress site with myCred plugin version <= 2.9.4.2.
• No authentication required.

Exploitation Steps:

1. Identify the vulnerable AJAX action (e.g., mycred_add_points).
2. Send a POST request to /wp-admin/admin-ajax.php with the action and required parameters.

Proof-of-Concept (PoC) using cURL:

curl -X POST http://target.com/wp-admin/admin-ajax.php \
  -d "action=mycred_add_points&user_id=1&points=1000"

Expected Result: The user with ID 1 receives 1000 points without authentication.

Blue Team (Defensive)

Detection:

• Monitor for unusual AJAX requests to admin-ajax.php with actions containing mycred_ from unauthenticated users.
• Look for rapid point changes or anomalies in user point balances.

Hunting Query (Splunk):

index=web sourcetype=access_combined
| search uri_path="/wp-admin/admin-ajax.php" AND form_data=*mycred_*
| eval auth_status=if(isnull(cookie), "unauthenticated", "authenticated")
| where auth_status="unauthenticated"
| stats count by src_ip, uri, form_data

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP POST requests to /wp-admin/admin-ajax.php with action=mycred_* parameters.
  • Unusual user agent strings or repeated requests from the same IP.
• Host IOCs:
  • Unexpected changes in wp_usermeta table for mycred_points or similar keys.
  • Log entries showing wp_ajax_mycred_* calls without authentication cookies.
• File IOCs:
  • Modified plugin files (e.g., mycred/includes/mycred-functions.php) if attacker uploads backdoor.

Detection Engineering

YARA Rule

rule CVE_2025_49857_myCred_Missing_Auth {
    meta:
        description = "Detects vulnerable myCred plugin files with missing authorization"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-49857"
    strings:
        $vuln_func = "add_action('wp_ajax_" nocase
        $no_cap = "current_user_can" nocase
    condition:
        #vuln_func > 0 and #no_cap == 0
}

Sigma Rule

title: CVE-2025-49857 myCred Missing Authorization Exploitation
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects unauthenticated AJAX requests to myCred plugin actions
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        c-uri: '/wp-admin/admin-ajax.php'
        cs-uri-query|contains: 'action=mycred_'
        sc-status: 200
    filter:
        c-uri|contains: 'nopriv'
    condition: selection and not filter
falsepositives:
    - Legitimate myCred AJAX calls from authenticated users (filtered by cookie)
level: high

Suricata Rule

alert http any any -> $HOME_NET any (
    msg:"CVE-2025-49857 myCred Missing Authorization Exploitation Attempt";
    flow:to_server,established;
    content:"POST";
    http_method;
    content:"/wp-admin/admin-ajax.php";
    http_uri;
    content:"action=mycred_";
    http_client_body;
    pcre:"/action=mycred_(?!nopriv)/";
    classtype:attempted-admin;
    sid:1000001;
    rev:1;
    reference:cve,2025-49857;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the myCred plugin until a patch is released.
2. If disabling is not possible, implement a Web Application Firewall (WAF) rule to block unauthenticated requests to admin-ajax.php with action=mycred_*.
3. Restrict access to admin-ajax.php via .htaccess or server config for unauthenticated users.

Long-term Fix:

• Monitor the myCred plugin page for updates and apply the patch immediately when available.
• Consider replacing myCred with an alternative plugin that has active security maintenance.

Workaround Code (Add to theme's functions.php):

add_action('init', function() {
    if (defined('DOING_AJAX') && DOING_AJAX) {
        $action = $_REQUEST['action'] ?? '';
        if (strpos($action, 'mycred_') === 0 && !is_user_logged_in()) {
            wp_die('Unauthorized', 403);
        }
    }
});

Valters IT
Securing Digital Frontiers