diff --git a/server/Application/Api/Model/AttachmentModel.class.php b/server/Application/Api/Model/AttachmentModel.class.php
index b518b9b57..f7781533d 100644
--- a/server/Application/Api/Model/AttachmentModel.class.php
+++ b/server/Application/Api/Model/AttachmentModel.class.php
@@ -311,6 +311,7 @@ public function isDangerFilename($filename){
 			|| $isDangerStr($filename , ".asa")
 			|| $isDangerStr($filename , ".cshtml")
 			|| $isDangerStr($filename , ".axd")
+			|| $isDangerStr($filename , "htm")
 		) {
 			return true;
 		}