Executive brief
HaxCMS, a content management system, is vulnerable to a security flaw that allows users with page-editing permissions to inject malicious scripts into website pages. If another user, such as an administrator, views the affected page and interacts with the injected content, the attacker could steal sensitive session data or perform unauthorized actions on their behalf. This could lead to a full takeover of the site or unauthorized access to private data.
Technical details
A stored Cross-Site Scripting (XSS) vulnerability exists in HaxCMS versions up to 26.0.0 within the `/system/api/saveNode` endpoint. The vulnerability is caused by a flaw in the regex-based HTML sanitizer, which fails to identify and strip event handler attributes (like 'onclick') if they are not preceded by whitespace (e.g., `href="#"onclick="..."`). An authenticated attacker with page-editing privileges can submit a crafted `node.body` parameter to inject malicious JavaScript. When a victim interacts with the injected element, the script executes in their browser context, potentially exposing JWTs in localStorage or application settings. The issue is addressed in version 26.0.1.
Affected products
- HaxTheWeb @haxtheweb/haxcms-nodejs <= 26.0.0
Timeline
- 2026-05-21: disclosed: Vulnerability reported to vendor
- 2026-05-29: advisory: GitHub Advisory published
- 2026-05-29: patched: Version 26.0.1 released