CSP Provider

'use client';
import * as React from 'react';
import { CSPProvider } from '@base-ui/react/csp-provider';
import { ScrollArea } from '@base-ui/react/scroll-area';
import styles from './index.module.css';

export default function ReactCspProvider() {
  const [disabled, setDisabled] = React.useState(false);
  return <div className={styles.Example}>
    <label className={styles.Label}><input type="checkbox" checked={disabled} onChange={event => setDisabled(event.target.checked)} />Disable style elements</label>
    <CSPProvider nonce="demo-nonce" disableStyleElements={disabled}>
      <ScrollArea.Root className={styles.Root}>
        <ScrollArea.Viewport className={styles.Viewport}>
          <ScrollArea.Content className={styles.Content}>
            {['Components can attach a nonce to the styles they generate.', 'Scroll this content to see the custom scrollbar.', 'Disable style elements to supply these rules in your own stylesheet.', 'Nested providers configure their own subtree.'].map(text => <p key={text}>{text}</p>)}
          </ScrollArea.Content>
        </ScrollArea.Viewport>
        <ScrollArea.Scrollbar className={styles.Scrollbar}><ScrollArea.Thumb className={styles.Thumb} /></ScrollArea.Scrollbar>
      </ScrollArea.Root>
    </CSPProvider>
  </div>;
}

Anatomy

Import the component and wrap it around your app:

import { CSPProvider } from '@base-ui/react/csp-provider';

<CSPProvider nonce="...">
  {/* Your app or a group of components */}
</CSPProvider>

Some Base UI components render inline <style> or <script> tags for functionality such as removing scrollbars or pre-hydration behavior. Under a strict Content Security Policy (CSP), these tags may be blocked unless they include a matching nonce attribute.

CSPProvider allows configuring this behavior globally for all Base UI components within its tree.

Supplying a nonce

If you enforce a CSP that blocks inline tags by default, configure your server to:

1. Generate a random nonce per request
2. Include it in your CSP header (via style-src-elem/script-src)
3. Pass the same nonce into CSPProvider during rendering

const nonce = crypto.randomUUID();

// Example CSP header
const csp = [`default-src 'self'`, `script-src 'self' 'nonce-${nonce}'`, `style-src-elem 'self' 'nonce-${nonce}'`].join('; ');

Then:

import { CSPProvider } from '@base-ui/react/csp-provider';

function App({ nonce }) {
  return <CSPProvider nonce={nonce}>{/* ... */}</CSPProvider>;
}

This will ensure that all inline <style> and <script> tags rendered by Base UI components include the correct nonce attribute, allowing them to function under your CSP.

Disable inline style elements

You can avoid supplying a nonce if you disable inline <style> elements entirely and rely on external stylesheets only. The relevant components are <ScrollArea.Viewport> and <Select.Popup> or <Select.List> when alignItemWithTrigger is enabled, which inject a style tag to disable native scrollbars.

<style>
  .base-ui-disable-scrollbar {
    scrollbar-width: none;
  }
  .base-ui-disable-scrollbar::-webkit-scrollbar {
    display: none;
  }
</style>

Specify disableStyleElements to remove these tags:

<CSPProvider disableStyleElements>{/* ... */}</CSPProvider>

<script> tags across all components are opt-in, so they are not affected by this prop and don’t have their own disable flag. A nonce is required if any component uses inline scripts.

Inline style attributes

CSPProvider covers inline <style> and <script> tags rendered as elements, but it does not cover inline style attributes (for example, <div style="...">). The style-src-attr directive in CSP governs inline style attributes encountered when parsing HTML from server pre-rendered components (it does not affect client-side JavaScript that sets styles).

In CSP, style-src applies to both <style> elements and style="" attributes. If you only want to control <style> elements, use style-src-elem instead.

If your CSP blocks inline style attributes in addition to elements, you have a few options:

1. Relax your CSP by adding 'unsafe-inline' to the style-src-attr directive (or using only style-src-elem instead of style-src). Style attributes specifically pose a less severe security risk than style elements, but this approach may not be acceptable in high-security environments.
2. Render the affected components only on the client, so that no inline styles are present in the initial HTML.
3. Manually unset inline styles and specify them in your CSS instead. Any component can have its inline styles unset, such as <ScrollArea.Viewport style={{ overflow: undefined }}>. Note that you’ll need to ensure you vet upgrades for any new inline styles added by Base UI components.

Stencil API

The Stencil provider is fs-csp-provider-root. Import the automatic registration entry, or call defineCustomElements() from finesoft-components/define-custom-elements before using the elements.

<fs-csp-provider-root nonce="request-nonce" disable-style-elements="false">
  <fs-scroll-area-root><!-- Scroll Area parts --></fs-scroll-area-root>
</fs-csp-provider-root>

The nearest provider replaces the complete configuration. A nested provider with no props enables style elements without inheriting the outer nonce. Portals retain their declaration scope. useCSPContext(element) reads the current configuration for custom consumers.

Like the frozen React style resource, the scrollbar stylesheet is emitted once per document or shadow root and remains after its consumers unmount. The first emission determines its nonce. disableStyleElements prevents emission; changing it later does not remove an existing shared stylesheet. Set the request nonce and disable flag before mounting consumers.

This provider configures the optional scrollbar <style> tags in Scroll Area and Select and the opt-in Tabs Indicator prehydration script. It leaves native style attributes unchanged. When disabling these tags, put the .base-ui-disable-scrollbar rules above in an external stylesheet.

Stencil also installs global component layout styles. Configure their nonce separately, before registration, with <meta name="csp-nonce" content="request-nonce"> or setNonce(requestNonce) from finesoft-components/define-custom-elements. Use the same request nonce in your CSP response header. A nested provider does not change the document-wide Stencil runtime nonce.

API reference

type CSPProviderState = {}