CVE-2025-49137 is a high-severity (CVSS 8.5) Cross-site Scripting (XSS) vulnerability in elmsln/haxcms. A fix is available for elmsln/haxcms — see the affected versions and patch details below.
Hax CMS Stored Cross-Site Scripting vulnerability
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-49137.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
elmsln/haxcmsReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
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
saveManifest() - Operations.php:868
saveNode() https://<site>/<user>/system/api/saveNodehttps://<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.
- Select "View Source" within the HAX site editor and enter an XSS payload that does not use the "script" HTML tag.
- Select "Update HTML" and observe the resulting alert.
saveManifest
To exploit the 'SaveManifest' endpoint, an attacker can insert executable code into the URL field of the site settings editor: any payload added this way will execute when the site is loaded.
- Open the site settings editor.
- Add JavaScript code to the URL field under the "Theme" header.
- Reload the page to run the script.
- The resulting page source will contain the script.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | elmsln/haxcms | all versions | 11.0.0composer require elmsln/haxcms:^11.0.0 |
Affected Products
haxcms-nodejspsuhaxcms-phppsuDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for elmsln/haxcms, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update elmsln/haxcms to 11.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-49137 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.
Frequently Asked Questions
Is CVE-2025-49137 in your dependencies?
Find it across Packagist, including transitive dependencies.