diff --git a/core/displayablegraph.class.inc.php b/core/displayablegraph.class.inc.php
index dced1517be..b7fbe7475b 100644
--- a/core/displayablegraph.class.inc.php
+++ b/core/displayablegraph.class.inc.php
@@ -1496,6 +1496,7 @@ function DisplayGraph(WebPage $oP, $sRelation, ApplicationContext $oAppContext,
 				'excluded'             => $aExcludedByClass,
 				'grouping_threshold'   => $iGroupingThreshold,
 				'export_as_pdf'        => array('url' => $sExportAsPdfURL, 'label' => Dict::S('UI:Relation:ExportAsPDF')),
+				'transaction_id'        => utils::GetNewTransactionId(),
 				'export_as_attachment' => array('url' => $sExportAsDocumentURL, 'label' => Dict::S('UI:Relation:ExportAsAttachment'), 'obj_class' => $sObjClass, 'obj_key' => $iObjKey),
 				'drill_down'           => array('url' => $sDrillDownURL, 'label' => Dict::S('UI:Relation:DrillDown')),
 				'labels'               => array(
diff --git a/js/simple_graph.js b/js/simple_graph.js
index 1e2980bc84..65ecedfe9b 100644
--- a/js/simple_graph.js
+++ b/js/simple_graph.js
@@ -19,6 +19,7 @@ $(function()
 					sources: {},
 					excluded: {},
 					export_as_pdf: null,
+					transaction_id: null,
 					page_format: { label: 'Page Format:', values: { A3: 'A3', A4: 'A4', Letter: 'Letter' }, 'default': 'A4'},
 					page_orientation: { label: 'Page Orientation:', values: { P: 'Portait', L: 'Landscape' }, 'default': 'L' },
 					labels: {
@@ -590,6 +591,7 @@ $(function()
 				var sHtmlForm = '<div id="GraphExportDlg'+this.element.attr('id')+'"><form id="graph_'+this.element.attr('id')+'_export_dlg" target="_blank" action="'+sSubmitUrl+'" method="post">';
 				sHtmlForm += '<input type="hidden" name="g" value="'+this.options.grouping_threshold+'">';
 				sHtmlForm += '<input type="hidden" name="context_key" value="'+this.options.context_key+'">';
+				sHtmlForm += '<input type="hidden" name="transaction_id" value="'+this.options.transaction_id+'">';
 				$('#'+sId+'_contexts').multiselect('getChecked').each(function() {
 					sHtmlForm += '<input type="hidden" name="contexts['+$(this).val()+']" value="'+me.options.additional_contexts[$(this).val()].oql+'">';
 				});
diff --git a/pages/ajax.render.php b/pages/ajax.render.php
index 2a2ff05e6b..cff8991a6f 100644
--- a/pages/ajax.render.php
+++ b/pages/ajax.render.php
@@ -32,15 +32,6 @@
 	require_once(APPROOT.'/application/startup.inc.php');
 	require_once(APPROOT.'/application/user.preferences.class.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'] !== 'GET') {
-		$sReferer = $_SERVER['HTTP_REFERER'];
-		$sErrorMsg = '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';
-		IssueLog::Error("Unprotected ajax call : $sErrorMsg", LogChannels::SECURITY, ['referer' => $sReferer]);
-		header('HTTP/1.1 401 Unauthorized');
-		die($sErrorMsg);
-	}
-
 	IssueLog::Trace('----- Request: '.utils::GetRequestUri(), LogChannels::WEB_REQUEST);
 	$oKPI = new ExecutionKPI();
 	$oKPI->ComputeAndReport('Data model loaded');
@@ -67,6 +58,20 @@
 			break;
 	}
 	LoginWebPage::DoLoginEx($sRequestedPortalId, false);
+
+	// check if header contains X-Combodo-Ajax for POST request (CSRF protection for ajax calls)
+	// check must be performed after DoLoginEx to be logged in and to be able to check the token (based on the transaction id)
+	if (!isset($_SERVER['HTTP_X_COMBODO_AJAX']) && $_SERVER['REQUEST_METHOD'] !== 'GET') {
+		$sTransactionId = utils::ReadPostedParam("transaction_id");
+		if (!utils::IsTransactionValid($sTransactionId, false)) { // if a form is submitted without header but contains a token... should be exceptional
+			$sReferer = $_SERVER['HTTP_REFERER'];
+			$sErrorMsg = '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';
+			IssueLog::Error("Unprotected ajax call : $sErrorMsg", LogChannels::SECURITY, ['referer' => $sReferer]);
+			header('HTTP/1.1 401 Unauthorized');
+			die($sErrorMsg);
+		}
+	}
+
 	$oKPI->ComputeAndReport('User login');
 
 	// N°2780 Fix ContextTag for console