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
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2025-49137 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
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 |
Detection & 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
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2025-49137 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2025-49137. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2025-49137 in your dependencies?
O3 Security finds CVE-2025-49137 across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.