HaxCMS has a stored Cross-Site Scripting (XSS) bypass in its saveNode endpoint

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

8.7 · CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N

EPSS

• CVE-2026-48527: 0.23% estimated exploitation activity in the next 30 days; percentile 13.64 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary HaxCMS is affected by a stored cross-site scripting (XSS) vulnerability in the /system/api/saveNode endpoint. An authenticated user with a permission to edit pages can bypass the HTML sanitizer by injecting an event handler attribute without whitespace before the attribute name. For example, the sanitizer misses: The important bypass is: The payload is stored in the generated page files and executes when a user clicks the injected link. Details The issue is caused by regex-based HTML sanitization that expects whitespace before event handler attributes. Because the sanitizer expects a pattern like: It fails to remove an event handler when it is written without whitespace: Browsers still parse onclick as a valid event handler attribute, so the JavaScript executes when the element is clicked. Affected endpoint: Affected parameter: PoC 1. Log in to HaxCMS and edit any existing page. 2. Capture the page save request in Burp Suite: 3. In the JSON request body, modify only the…

Published by the source

29 May 2026, 14:07 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 12:53 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-g2g8-95qg-v35h

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-g2g8-95qg-v35h

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# Patch Next advisory brief: CVE-2026-48527

Advisory: HaxCMS has a stored Cross-Site Scripting (XSS) bypass in its saveNode endpoint
IDs: CVE-2026-48527, GHSA-g2g8-95qg-v35h
Record: https://patchnext.com/advisories/cve-2026-48527 (revision 2, source checked 26 Oct 2026, 12:53 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: @haxtheweb/haxcms-nodejs 26.0.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm @haxtheweb/haxcms-nodejs: affected <= 26.0.0; fixed in 26.0.1

## Suggested inspection (read-only)
- `npm ls @haxtheweb/haxcms-nodejs --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on @haxtheweb/haxcms-nodejs.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-g2g8-95qg-v35h (OSV record GHSA-g2g8-95qg-v35h lists affected ranges: npm @haxtheweb/haxcms-nodejs >=0 <26.0.1 (fixed))
- Verified: https://github.com/advisories/GHSA-g2g8-95qg-v35h (GitHub-reviewed advisory GHSA-g2g8-95qg-v35h lists affected ranges: npm @haxtheweb/haxcms-nodejs >=0 <=26.0.0)

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