CSRF Protection

Slim 3 uses the optional standalone slimphp/Slim-Csrf PHP component to protect your application from CSRF (cross-site request forgery). This component generates a unique token per request that validates subsequent POST requests from client-side HTML forms.


Execute this bash command from your project’s root directory:

composer require slim/csrf


The slimphp/Slim-Csrf component contains an application middleware. Add it to your application like this:

// Add middleware to the application
$app = new \Slim\App;
$app->add(new \Slim\Csrf\Guard);

// Create your application routes...

// Run application

Fetch the CSRF token name and value

The latest CSRF token’s name and value are available as attributes on the PSR7 request object. The CSRF token name and value are unique for each request. You can fetch the current CSRF token name and value like this.

$app->get('/foo', function ($req, $res, $args) {
    // CSRF token name and value
    $nameKey = $this->csrf->getTokenNameKey();
    $valueKey = $this->csrf->getTokenValueKey();
    $name = $req->getAttribute($nameKey);
    $value = $req->getAttribute($valueKey);

    // Render HTML form which POSTs to /bar with two hidden input fields for the
    // name and value:
    // <input type="hidden" name="<?= $nameKey ?>" value="<?= $name ?>">
    // <input type="hidden" name="<?= $valueKey ?>" value="<?= $value ?>">

$app->post('/bar', function ($req, $res, $args) {
    // CSRF protection successful if you reached
    // this far.

You should pass the CSRF token name and value to the template so they may be submitted with HTML form POST requests. They are often stored as a hidden field with HTML forms.

For more use cases and documentation please check slimphp/Slim-Csrf’s page.