CVE-2025-49137: Critical Vulnerability in HAX CMS PHP Prior to Version 11.0.0

Overview

In this blog post, we delve into an alarming vulnerability, CVE-2025-49137, that resides in HAX CMS PHP, a widely-used content management system that allows users to manage their microsite universe with a PHP backend. This critical security flaw, discovered before the release of version 11.0.0, stems from an inadequate sanitization of user input, leaving the door wide open for the execution of arbitrary JavaScript code. This vulnerability is particularly significant due to its potential to compromise the system or leak sensitive data, thereby posing a severe risk to the privacy and security of users and entities alike.

Vulnerability Summary

CVE ID: CVE-2025-49137
Severity: Critical (8.5 CVSS Score)
Attack Vector: Network
Privileges Required: None
User Interaction: Required
Impact: Potential system compromise and data leakage

Affected Products

Product | Affected Versions

HAX CMS PHP | Prior to 11.0.0

How the Exploit Works

The exploit operates by leveraging the application’s failure to sanitize user input sufficiently. Although the application does not permit users to supply a `script` tag, it does allow the use of other HTML tags to run JavaScript. The ‘saveNode’ and ‘saveManifest’ endpoints accept user input and store it in the JSON schema for the site. The malicious content is then rendered in the generated HAX site, paving the way for the execution of arbitrary JavaScript code, which could potentially compromise the system or lead to data leakage.

Conceptual Example Code

Here’s a conceptual example of how this vulnerability may be exploited:

POST /saveNode HTTP/1.1
Host: target.example.com
Content-Type: application/json
{
"node_data": "<img src='x' onerror='javascript:malicious_code'>"
}

In this example, a malicious user uses an `img` tag with an `onerror` attribute to inject arbitrary JavaScript code into the HAX CMS PHP application. When the malformed `img` tag loads and the error is triggered, the malicious JavaScript code executes.

Mitigation Guidance

To mitigate this vulnerability, users should apply the vendor-provided patch immediately, upgrading their HAX CMS PHP to version 11.0.0 or later. As a temporary measure, users can also employ a Web Application Firewall (WAF) or an Intrusion Detection System (IDS) to detect and prevent potential exploitation attempts.