diff --git a/modules/comment/comment.controller.php b/modules/comment/comment.controller.php
index 45cc35706..83c854e44 100644
--- a/modules/comment/comment.controller.php
+++ b/modules/comment/comment.controller.php
@@ -677,23 +677,26 @@ class CommentController extends Comment
 		}
 
 		// if use editor of nohtml, Remove HTML tags from the contents.
-		if(!$manual_inserted || isset($obj->allow_html) || isset($obj->use_html))
+		if (!$manual_inserted || isset($obj->allow_html) || isset($obj->use_html))
 		{
 			$obj->content = EditorModel::converter($obj, 'comment');
 		}
 
 		// remove iframe and script if not a top administrator on the session.
-		if($logged_info->is_admin != 'Y')
+		if ($logged_info->is_admin !== 'Y')
 		{
-			$obj->content = removeHackTag($obj->content);
+			$obj->content = Rhymix\Framework\Filters\HTMLFilter::clean((string)$obj->content);
+		}
+		if (config('db.master.charset') !== 'utf8mb4')
+		{
+			$obj->content = utf8_mbencode($obj->content);
 		}
-		$obj->content = utf8_mbencode($obj->content);
 
+		// Set other flags.
 		if (isset($obj->notify_message) && $obj->notify_message !== 'Y')
 		{
 			$obj->notify_message = 'N';
 		}
-
 		if (isset($obj->is_secret) && $obj->is_secret !== 'Y')
 		{
 			$obj->is_secret = 'N';
@@ -1042,11 +1045,14 @@ class CommentController extends Comment
 
 		// remove iframe and script if not a top administrator on the session
 		$logged_info = Context::get('logged_info');
-		if($logged_info->is_admin != 'Y')
+		if ($logged_info->is_admin !== 'Y')
 		{
-			$obj->content = removeHackTag($obj->content);
+			$obj->content = Rhymix\Framework\Filters\HTMLFilter::clean((string)$obj->content);
+		}
+		if (config('db.master.charset') !== 'utf8mb4')
+		{
+			$obj->content = utf8_mbencode($obj->content);
 		}
-		$obj->content = utf8_mbencode($obj->content);
 
 		// begin transaction
 		$oDB = DB::getInstance();
diff --git a/modules/communication/communication.controller.php b/modules/communication/communication.controller.php
index 4064fb333..72ff49fa9 100644
--- a/modules/communication/communication.controller.php
+++ b/modules/communication/communication.controller.php
@@ -184,9 +184,12 @@ class CommunicationController extends communication
 	{
 		// Encode the title and content.
 		$title = escape($title, false);
-		$content = removeHackTag($content);
-		$title = utf8_mbencode($title);
-		$content = utf8_mbencode($content);
+		$content = Rhymix\Framework\Filters\HTMLFilter::clean((string)$content);
+		if (config('db.master.charset') !== 'utf8mb4')
+		{
+			$title = utf8_mbencode($title);
+			$content = utf8_mbencode($content);
+		}
 
 		$message_srl = $temp_srl ?: getNextSequence();
 		$related_srl = getNextSequence();
@@ -309,7 +312,7 @@ class CommunicationController extends communication
 
 		$mail_content = vsprintf('From: %s<br><hr><br>%s<br><hr><br>%s<br><a href="%s" target="_blank">%s</a>', [
 			$sender->nick_name,
-			utf8_mbencode(removeHackTag($content)),
+			utf8_mbencode(Rhymix\Framework\Filters\HTMLFilter::clean((string)$content)),
 			Context::getSiteTitle(),
 			$view_url, $view_url,
 		]);
diff --git a/modules/document/document.controller.php b/modules/document/document.controller.php
index 42e98a181..9b3cc0618 100644
--- a/modules/document/document.controller.php
+++ b/modules/document/document.controller.php
@@ -811,24 +811,31 @@ class DocumentController extends Document
 		}
 
 		// if use editor of nohtml, Remove HTML tags from the contents.
-		if(!$manual_inserted || isset($obj->allow_html) || isset($obj->use_html))
+		if (!$manual_inserted || isset($obj->allow_html) || isset($obj->use_html))
 		{
 			$obj->content = EditorModel::converter($obj, 'document');
 		}
 
 		// Remove iframe and script if not a top adminisrator in the session.
-		if($logged_info->is_admin != 'Y')
+		if ($logged_info->is_admin !== 'Y')
 		{
-			$obj->content = removeHackTag($obj->content);
+			$obj->content = Rhymix\Framework\Filters\HTMLFilter::clean((string)$obj->content);
+		}
+
+		// Fix encoding of non-BMP UTF-8 characters.
+		if (config('db.master.charset') !== 'utf8mb4')
+		{
+			$obj->title = utf8_mbencode($obj->title);
+			$obj->content = utf8_mbencode($obj->content);
 		}
 
 		// An error appears if both log-in info and user name don't exist.
-		if(!$logged_info->member_srl && !$obj->nick_name) return new BaseObject(-1, 'msg_invalid_request');
-
-		// Fix encoding of non-BMP UTF-8 characters.
-		$obj->title = utf8_mbencode($obj->title);
-		$obj->content = utf8_mbencode($obj->content);
+		if (!$logged_info->member_srl && !$obj->nick_name)
+		{
+			return new BaseObject(-1, 'msg_invalid_request');
+		}
 
+		// Set lang_code to the current user's language
 		$obj->lang_code = Context::getLangType();
 
 		// begin transaction
@@ -1167,14 +1174,17 @@ class DocumentController extends Document
 		}
 
 		// Remove iframe and script if not a top adminisrator in the session.
-		if($logged_info->is_admin != 'Y')
+		if ($logged_info->is_admin !== 'Y')
 		{
-			$obj->content = removeHackTag($obj->content);
+			$obj->content = Rhymix\Framework\Filters\HTMLFilter::clean((string)$obj->content);
 		}
 
 		// Fix encoding of non-BMP UTF-8 characters.
-		$obj->title = utf8_mbencode($obj->title);
-		$obj->content = utf8_mbencode($obj->content);
+		if (config('db.master.charset') !== 'utf8mb4')
+		{
+			$obj->title = utf8_mbencode($obj->title);
+			$obj->content = utf8_mbencode($obj->content);
+		}
 
 		// Begin transaction
 		$oDB = DB::getInstance();
diff --git a/modules/document/document.view.php b/modules/document/document.view.php
index 73f6a7086..415293993 100644
--- a/modules/document/document.view.php
+++ b/modules/document/document.view.php
@@ -55,11 +55,10 @@ class DocumentView extends Document
 			throw new Rhymix\Framework\Exceptions\SecurityViolation;
 		}
 
-		$content = Context::get('content');
-
-		if(Context::get('logged_info')->is_admin != 'Y')
+		$content = (string)Context::get('content');
+		if (Context::get('logged_info')->is_admin !== 'Y')
 		{
-			$content = removeHackTag($content);
+			$content = Rhymix\Framework\Filters\HTMLFilter::clean($content);
 		}
 
 		// Editor converter