diff --git a/server/Application/Api/Model/AttachmentModel.class.php b/server/Application/Api/Model/AttachmentModel.class.php
index d84898984..32fb24799 100644
--- a/server/Application/Api/Model/AttachmentModel.class.php
+++ b/server/Application/Api/Model/AttachmentModel.class.php
@@ -300,6 +300,7 @@ public function isDangerFilename($filename){
 			 $isDangerStr($filename , ".php")
 			|| $isDangerStr($filename , ".svg")
 			|| $isDangerStr($filename , ".htm")
+			|| $isDangerStr($filename , ".shtm")
 			|| $isDangerStr($filename , "%")
 			|| $isDangerStr($filename , ".xml")
 		) {