> For the complete documentation index, see [llms.txt](https://clients.medianova.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://clients.medianova.com/products/performance-cdn/static-content-delivery/advanced-configuration/headers/x-xss-protection.md).

# X-XSS Protection

Learn how the X-XSS Protection header controls browser-side filtering of reflected Cross-Site Scripting (XSS) attacks.

**X-XSS-Protection** adds the `X-XSS-Protection` header to viewer-facing responses. Browsers that support this header use their built-in XSS filtering mechanisms to detect and block certain reflected XSS attacks.

Modern browsers generally rely on `Content-Security-Policy` instead of this header. X-XSS-Protection is primarily intended for environments that require legacy browser compatibility.

You can configure X-XSS-Protection in the [Medianova Control Panel](https://cloud.medianova.com) or via the [API](https://clients.medianova.com/api-documentation/performance-cdn/headers#put-api-v1-cdn-organization_uuid-resource-resource_uuid-6).

{% hint style="info" %}
X-XSS-Protection is a legacy browser security mechanism. It does not replace modern protections such as Content Security Policy (CSP).
{% endhint %}

## Configure X-XSS-Protection

{% stepper %}
{% step %}

### Open X-XSS-Protection

Open your CDN Resource and select **Headers**.

<figure><img src="https://542970813-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FtK7oIwmhUHdEJcaH4Hx8%2Fuploads%2FJs88HacQVoathWuisbhF%2Fimage.png?alt=media&amp;token=09c7f2c2-a34b-4eef-8e60-f02dc973a05b" alt=""><figcaption></figcaption></figure>

Locate the **X-XSS-Protection** section.
{% endstep %}

{% step %}

### Enable X-XSS-Protection

Enable **X-XSS-Protection**.

When enabled, the CDN adds the following header to viewer-facing responses:

```http
X-XSS-Protection: 1; mode=block
```

{% endstep %}

{% step %}

### Save the Configuration

Click **Save** in the pending changes bar.

Review the pending changes and confirm the update.
{% endstep %}
{% endstepper %}

## Behavior

When X-XSS-Protection is enabled:

* The CDN adds `X-XSS-Protection: 1; mode=block` to viewer-facing responses.
* Browsers that support the header can block pages that trigger reflected XSS heuristics.
* Modern browsers may ignore this header and rely on `Content-Security-Policy` for XSS mitigation.
* The header does not protect against stored or DOM-based XSS attacks.
* The setting does not affect origin requests or CDN caching behavior.

When X-XSS-Protection is disabled, the CDN does not add this header through this feature.


---

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