Http header beheer

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This page is a translated version of the page J4.x:Http Header Management and the translation is 56% complete.
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Hoe het nieuwe HTTP header beheer gebruiken in Joomla 4.0

Vanaf Joomla 4.0, heeft Joomla een HTTP Header beheersysteem ingevoerd. Dit systeem is ontworpen om eigenaren van websites te helpen de HTTP Security Headers vanuit het beheergedeelte in te stellen.

In deze handleiding vind je informatie hoe dit nieuwe systeem in te stellen op je website.


Systeem - HTTP Headers (plg_system_httpheaders)

Navigeer naar Systeem  Plugins  Systeem - HTTP Headers om bij de instellingen van de plugin te komen.

Plugin instelling

Vanuit deze pagina kun je er voor kiezen om in te schakelen dat de headers weggeschreven worden naar de server instellingen bestanden (.htaccess en web.config) en instellen of de volgende http headers ingeschakeld zijn.

Met het formulier "Force Header" kunt u ook de volgende headers forceren met de bijbehorende waarden:


Strict-Transport-Security (HSTS) instellingen

Vanaf deze pagina kun je er voor kiezen dat de Strict-Transport-Security (HSTS) header ingeschakeld is evenals het instellen van de max-age waarde, of subdomeinen opgenomen moeten worden en of het toegevoegd moet worden aan de preload-lijst van de browser.


Content-Security-Policy (CSP) Configuration

From this page you can choose to enable and configure the Content-Security-Policy (CSP) header set by the plugin.


Once enabled you can set the client where you want to enforce the configured CSP on, allowing you to set set "site", "administrator" or "both".

The following settings need a bit more explanation, thats also the reason there are additional descriptions on all of them.

The final option called "Add Directive" allows you to configure the allowlist per directive as you need them. For example the directive "script-src" where the option "Value" you enter the origins you want to allow to load scripts from.


When you have configured some HTTP Security Headers directly on the server, then our tooling might create double entries.

Check the output of your HTTP Headers after configuring in the browser console. In Google Chrome: Inspect > Network > the output under Headers). You can than disable the headers that cause double entries. Also check the console of your browser for possible errors.

Extension Developers

As you might know the big security advantage concerning Content Security Policy jumps in when we can use the Header to block all inline JavaScript and inline CSS affecting for example JavaScript event handlers via HTML attributes. So with this browser protection enabled we will block inline JavaScript and inline CSS usage also for your extensions. That protection is not enabled by default but can be enabled by your users.

For 4.0 it would be recommended to get the frontend of your extension running with strict Content Security Policy enabled. For 4.1 compatibility it would be recommended that this also applies to your backend.

We know that it is still a requirement to have inline JavaScript and CSS, for that reason we have implemented nonce and hash support into our Document APIs when you use them the core will make sure they are whitelisted but we will still block any malicious to protect our sites.

Important notes for Extension Developers

Starting with Joomla 4.0 Content Security Policy:

  • is shipped by the core
  • is disabled by default
  • can be enabled by your users
  • it is strongly recommended that your extension frontend works by 4.0 with Content Security Policy enabled
  • it is recommended that your extension backend works by 4.1 with Content Security Policy enabled

With strict Content Security Policy enabled the following features will be blocked:

  • the execution of JavaScript via the HTML event handlers (onXXX handlers like onClick and similar)
  • the execution of in-page JavaScript not passed to the page via the Document API
  • the execution of JavaScript code injected into DOM APIs such as eval()
  • the usage of inline in-page CSS not passed to the page via the Document API
  • the usage of inline CSS using the HTML style attribute

To get your extensions work even with strict Content Security Policy enabled, the easiest way is to use the Document API to apply your inline JavaScript and CSS, please check the examples below.

Adding JavaScript using the Joomla API

use Joomla\CMS\Factory;

/** @var Joomla\CMS\WebAsset\WebAssetManager $wa */
$wa = Factory::getApplication()->getDocument()->getWebAssetManager();

// Add JavaScript from URL
$wa->registerAndUseScript('com_example.sample', 'https://example.org/sample.js', [], ['defer' => true]);

// Add inline JavaScript
    document.addEventListener("DOMContentLoaded", function(event) {
        alert("An inline JavaScript Declaration");

Adding CSS using the Joomla API

use Joomla\CMS\Factory;

/** @var Joomla\CMS\WebAsset\WebAssetManager $wa */
$wa = Factory::getApplication()->getDocument()->getWebAssetManager();

// Add Style from URL
$wa->registerAndUseStyle('com_example.sample', 'https://example.org/sample.css');

// Add inline Style
	body {
		background: #00ff00;
		color: rgb(0,0,255);

More details can be found here:Adding JavaScript and CSS to the page

Additional resources about Content Security Policy and HTTP Headers