diff --git a/typo3/sysext/backend/Classes/Controller/PageLayoutController.php b/typo3/sysext/backend/Classes/Controller/PageLayoutController.php
index 0188221a2f1d68323c3926f53e0298cbc9544b40..e356a54e264a7f8dcffb04e19aefb3459aa20cea 100644
--- a/typo3/sysext/backend/Classes/Controller/PageLayoutController.php
+++ b/typo3/sysext/backend/Classes/Controller/PageLayoutController.php
@@ -674,7 +674,7 @@ class PageLayoutController
                 'mainJsFunctions',
                 'if (top.fsMod) top.fsMod.recentIds["web"] = ' . (int)$this->id . ';'
             );
-            $content .= '<h1>' . $GLOBALS['TYPO3_CONF_VARS']['SYS']['sitename'] . '</h1>';
+            $content .= '<h1>' . htmlspecialchars($GLOBALS['TYPO3_CONF_VARS']['SYS']['sitename']) . '</h1>';
             $view = GeneralUtility::makeInstance(StandaloneView::class);
             $view->setTemplatePathAndFilename(GeneralUtility::getFileAbsFileName('EXT:backend/Resources/Private/Templates/InfoBox.html'));
             $view->assignMultiple([