diff --git a/js/ckeditor.feeds.js b/js/ckeditor.feeds.js
index f6bbe312f..b06279602 100644
--- a/js/ckeditor.feeds.js
+++ b/js/ckeditor.feeds.js
@@ -16,7 +16,11 @@ const CombodoCKEditorFeeds = {
 		return async function(queryText) {
 			return new Promise( resolve => {
 				setTimeout( () => {
-					fetch(options.url + queryText)
+					fetch(options.url + queryText, {
+						headers: {
+							'X-Combodo-Ajax': true
+						}
+					})
 						.then(response => {
 							return response.json();
 						})
diff --git a/js/ckeditor.handler.js b/js/ckeditor.handler.js
index 59293f913..390cd29a5 100644
--- a/js/ckeditor.handler.js
+++ b/js/ckeditor.handler.js
@@ -115,6 +115,9 @@ const CombodoCKEditorHandler = {
 								fetch(uploadUrl, {
 									method: 'POST',
 									body: formData,
+									headers: {
+										'X-Combodo-Ajax': true
+									},
 								})
 									.then(response => response.json())
 									.then(responseData => {
diff --git a/pages/ajax.render.php b/pages/ajax.render.php
index 02e346b18..89135c9db 100644
--- a/pages/ajax.render.php
+++ b/pages/ajax.render.php
@@ -27,6 +27,16 @@ use Combodo\iTop\Service\TemporaryObjects\TemporaryObjectManager;
 
 require_once('../approot.inc.php');
 
+
+// check if header contains X-Combodo-Ajax for POST request (CSRF protection for ajax calls)
+if (!isset($_SERVER['HTTP_X_COMBODO_AJAX']) && $_SERVER['REQUEST_METHOD'] === 'POST') {
+	$sReferer = utils::HtmlEntities($_SERVER['HTTP_REFERER']);
+	IssueLog::Error("Unprotected ajax call from: $sReferer", 'SECURITY');
+	header('HTTP/1.1 401 Unauthorized');
+	die('Unauthorized access. Please see https://www.itophub.io/wiki/page?id=3_2_0:release:developer#checking_for_the_presence_of_specific_header_in_the_post_to_enhance_protection_against_csrf_attacks');
+}
+
+
 function LogErrorMessage($sMsgPrefix, $aContextInfo) {
 	$sCurrentUserLogin = UserRights::GetUser();
 	$sContextInfo = urldecode(http_build_query($aContextInfo, '', ', '));