diff --git a/snappymail/v/0.0.0/app/handle.php b/snappymail/v/0.0.0/app/handle.php
index 8c4d2dffe..be12952aa 100644
--- a/snappymail/v/0.0.0/app/handle.php
+++ b/snappymail/v/0.0.0/app/handle.php
@@ -28,6 +28,11 @@ if (!\defined('RAINLOOP_APP_LIBRARIES_PATH'))
 
 if (\class_exists('RainLoop\Api'))
 {
+	if (!\SnappyMail\HTTP\SecFetch::site('same-origin')
+	 && !\SnappyMail\HTTP\SecFetch::site('none')) {
+		 exit('Invalid Sec-Fetch');
+	}
+
 	\MailSo\Base\Loader::Init();
 
 	if (!empty($_ENV['RAINLOOP_INCLUDE_AS_API']))
diff --git a/snappymail/v/0.0.0/app/libraries/snappymail/http/secfetch.php b/snappymail/v/0.0.0/app/libraries/snappymail/http/secfetch.php
new file mode 100644
index 000000000..34eb7f598
--- /dev/null
+++ b/snappymail/v/0.0.0/app/libraries/snappymail/http/secfetch.php
@@ -0,0 +1,95 @@
+<?php
+
+namespace SnappyMail\HTTP;
+
+abstract class SecFetch
+{
+	/**
+	 * audio
+	 *   The destination is audio data. This might originate from an HTML <audio> tag.
+	 * audioworklet
+	 *   The destination is data being fetched for use by an audio worklet. This might originate from a call to audioWorklet.addModule().
+	 * document
+	 *   The destination is a document (HTML or XML), and the request is the result of a user-initiated top-level navigation (e.g. resulting from a user clicking a link).
+	 * embed
+	 *   The destination is embedded content. This might originate from an HTML <embed> tag.
+	 * empty
+	 *   The destination is the empty string. This is used for destinations that do not have their own value. For exmaple fetch(), navigator.sendBeacon(), EventSource, XMLHttpRequest, WebSocket, etc.
+	 * font
+	 *   The destination is a font. This might originate from CSS @font-face.
+	 * frame
+	 *   The destination is a frame. This might originate from an HTML <frame> tag.
+	 * iframe
+	 *   The destination is an iframe. This might originate from an HTML <iframe> tag.
+	 * image
+	 *   The destination is an image. This might originate from an HTML <image>, SVG <image>, CSS background-image, CSS cursor, CSS list-style-image, etc.
+	 * manifest
+	 *   The destination is a manifest. This might originate from an HTML <link rel=manifest>).
+	 * object
+	 *   The destination is an object. This might originate from an HTML <object> tag.
+	 * paintworklet
+	 *   The destination is a paint worklet. This might originate from a call to CSS.PaintWorklet.addModule().
+	 * report
+	 *   The destination is a report (for exmaple, a content security policy report).
+	 * script
+	 *   The destination is a script. This might originate from an HTML <script> tag or a call to WorkerGlobalScope.importScripts().
+	 * serviceworker
+	 *   The destination is a service worker. This might originate from a call to navigator.serviceWorker.register().
+	 * sharedworker
+	 *   The destination is a shared worker. This might originate from a SharedWorker.
+	 * style
+	 *   The destination is a style. This might originate from an HTML <link rel=stylesheet> or a CSS @import.
+	 * track
+	 *   The destination is an HTML text track. This might originate from an HTML <track> tag.
+	 * video
+	 *   The destination is video data. This might originate from an HTML <video> tag.
+	 * worker
+	 *   The destination is a Worker.
+	 * xslt
+	 *   The destination is an XLST transform.
+	 */
+	public static function dest(string $type) : bool
+	{
+		return $type == ($_SERVER['HTTP_SEC_FETCH_DEST'] ?? '');
+	}
+
+	/**
+	 * cors
+	 *   The request is a CORS protocol request.
+	 * navigate
+	 *   The request is initiated by navigation between HTML documents.
+	 * no-cors
+	 *   The request is a no-cors request.
+	 * same-origin
+	 *   The request is made from the same origin as the resource that is being requested.
+	 * websocket
+	 *   The request is being made to establish a WebSocket connection.
+	 */
+	public static function mode(string $type) : bool
+	{
+		return $type == ($_SERVER['HTTP_SEC_FETCH_MODE'] ?? '');
+	}
+
+	/**
+	 * cross-site
+	 *   The request initiator and the server hosting the resource have a different
+	 *   site (i.e. a request by "potentially-evil.com" for a resource at "example.com").
+	 * same-origin
+	 *   The request initiator and the server hosting the resource have the same origin (same scheme, host and port).
+	 * same-site
+	 *   The request initiator and the server hosting the resource have the same scheme,
+	 *   domain and/or subdomain, but not necessarily the same port.
+	 * none
+	 *   This request is a user-originated operation. For example: entering a URL into the address bar,
+	 *   opening a bookmark, or dragging-and-dropping a file into the browser window.
+	 */
+	public static function site(string $type) : bool
+	{
+		return $type == ($_SERVER['HTTP_SEC_FETCH_SITE'] ?? 'none');
+	}
+
+	public static function user() : bool
+	{
+		return '?1' == ($_SERVER['HTTP_SEC_FETCH_USER'] ?? '');
+	}
+}