Hax CMS Stored Cross-Site Scripting vulnerability
Date: 2025-06
Affected: composer/elmsln/haxcms
Attack vector: xss
Category: vulnerability-disclosure
Severity: High
CVE: CVE-2025-49137
CWE: CWE-79
CWE-80
CWE-87
CVSS: 8.5 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N)

### Summary The application does not sufficiently sanitize user input, allowing for the execution of arbitrary JavaScript code. The 'saveNode' and 'saveManifest' endpoints take user input and store it in the JSON schema for the site. This content is then rendered in the generated HAX site. Although the application does not allow users to supply a 'script' tag, it does allow the use of other HTML tags to run JavaScript. ### Affected Resources - [Operations.php:258](https://github.com/haxtheweb/haxcms-php/blob/master/system/backend/php/lib/Operations.php#L258) `saveManifest()` - [Operations.php:868](https://github.com/haxtheweb/haxcms-php/blob/master/system/backend/php/lib/Operations.php#L868) `saveNode()` - `https://<site>/<user>/system/api/saveNode` - `https://<site>/<user>/system/api/saveManifest` ### Impact An authenticated attacker can use the site editor and settings editor to store malicious payloads in a HAX site which execute arbitrary JavaScript when a user visits the site. This can be used to steal a user's session cookie or other sensitive data. ### PoCs #### saveNode To replicate this vulnerability, an attacker can use the "View Source" functionality within the site editor to enter a malicious payload. 1. Select "View Source" within the HAX site editor and enter an XSS payload that does not use the "script" HTML tag. ![image](https://github.com/user-attachments/assets/c22c52e6-079a-4add-94a2-b51b1a925a96) 3. Select "Update HTML" and observe the resultin


Mitigations:

Architectural layers (MAESTRO):