Content Security Policy MiddlewareΒΆ

The CspMiddleware makes it simpler to add Content-Security-Policy headers in your application. Before using it you should install paragonie/csp-builder:

composer require paragonie/csp-builder

You can then configure the middleware using an array, or passing in a built CSPBuilder object:

use Cake\Http\Middleware\CspMiddleware;

$csp = new CspMiddleware([
    'script-src' => [
        'allow' => [
        'self' => true,
        'unsafe-inline' => false,
        'unsafe-eval' => false,


If you want to use a more strict CSP configuration, you can enable nonce based CSP rules with the scriptNonce and styleNonce options. When enabled these options will modify your CSP policy and set the cspScriptNonce and cspStyleNonce attributes in the request. These attributes are applied to the nonce attribute of all script and CSS link elements created by HtmlHelper. This simplifies the adoption of policies that use a nonce-base64 and strict-dynamic for increased security and easier maintenance:

$policy = [
    // Must exist even if empty to set nonce for for script-src
    'script-src' => [],
    'style-src' => [],
// Enable automatic nonce addition to script & CSS link tags.
$csp = new CspMiddleware($policy, [
    'scriptNonce' => true,
    'styleNonce' => true,