diff --git a/src/java/fr/paris/lutece/plugins/newsletter/service/NewsLetterRegistrationService.java b/src/java/fr/paris/lutece/plugins/newsletter/service/NewsLetterRegistrationService.java
index 471a048..79a7bf6 100644
--- a/src/java/fr/paris/lutece/plugins/newsletter/service/NewsLetterRegistrationService.java
+++ b/src/java/fr/paris/lutece/plugins/newsletter/service/NewsLetterRegistrationService.java
@@ -33,11 +33,11 @@
  */
 package fr.paris.lutece.plugins.newsletter.service;
 
+import java.security.SecureRandom;
 import java.sql.Timestamp;
 import java.util.Date;
 import java.util.HashMap;
 import java.util.Map;
-import java.util.Random;
 import  java.util.Collection;
 import javax.servlet.http.HttpServletRequest;
 import org.apache.commons.lang3.StringUtils;
@@ -189,7 +189,7 @@ public void doSubscription( HttpServletRequest request ) throws SiteMessageExcep
             if ( properties.isValidationActive( ) )
             {
                 // generate validation key
-                Random random = new Random( );
+                SecureRandom random = new SecureRandom( );
                 int nAlea = random.nextInt( );
                 // add pair in db
                 AwaitingActivationHome.create( subscriber.getId( ), nAlea, getPlugin( ) );
diff --git a/src/java/fr/paris/lutece/plugins/newsletter/util/HtmlDomDocNewsletter.java b/src/java/fr/paris/lutece/plugins/newsletter/util/HtmlDomDocNewsletter.java
index 040ab7c..474dfa5 100644
--- a/src/java/fr/paris/lutece/plugins/newsletter/util/HtmlDomDocNewsletter.java
+++ b/src/java/fr/paris/lutece/plugins/newsletter/util/HtmlDomDocNewsletter.java
@@ -40,8 +40,8 @@
 import java.io.StringWriter;
 import java.io.UnsupportedEncodingException;
 
+import javax.xml.XMLConstants;
 import javax.xml.transform.Transformer;
-import javax.xml.transform.TransformerConfigurationException;
 import javax.xml.transform.TransformerException;
 import javax.xml.transform.TransformerFactory;
 import javax.xml.transform.dom.DOMSource;
@@ -206,6 +206,8 @@ public String getContent( )
         StringWriter writer = new StringWriter( );
         StreamResult result = new StreamResult( writer );
         TransformerFactory tf = TransformerFactory.newInstance( );
+        tf.setAttribute(XMLConstants.ACCESS_EXTERNAL_DTD, "");
+        tf.setAttribute(XMLConstants.ACCESS_EXTERNAL_STYLESHEET, "");
         Transformer transformer;
 
         try
@@ -213,12 +215,6 @@ public String getContent( )
             transformer = tf.newTransformer( );
             transformer.transform( domSource, result );
         }
-        catch( TransformerConfigurationException e )
-        {
-            AppLogService.error( e.getMessage( ) );
-
-            return null;
-        }
         catch( TransformerException e )
         {
             AppLogService.error( e.getMessage( ) );
@@ -226,9 +222,8 @@ public String getContent( )
             return null;
         }
 
-        String stringResult = writer.toString( );
+        return writer.toString( );
 
-        return stringResult;
     }
 
     /**
diff --git a/src/java/fr/paris/lutece/plugins/newsletter/web/NewsletterTemplateJspBean.java b/src/java/fr/paris/lutece/plugins/newsletter/web/NewsletterTemplateJspBean.java
index 9157755..c91973f 100644
--- a/src/java/fr/paris/lutece/plugins/newsletter/web/NewsletterTemplateJspBean.java
+++ b/src/java/fr/paris/lutece/plugins/newsletter/web/NewsletterTemplateJspBean.java
@@ -74,6 +74,7 @@
 import java.io.FileReader;
 import java.io.FileWriter;
 import java.io.IOException;
+import java.nio.file.Files;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashMap;
@@ -444,7 +445,9 @@ public String doModifyNewsletterTemplate( HttpServletRequest request )
                         String strPathFileNewsletterTemplate = AppPathService.getPath( PROPERTY_PATH_TEMPLATE )
                                 + AppPropertiesService.getProperty( NewsLetterConstants.PROPERTY_PATH_FILE_NEWSLETTER_TEMPLATE );
                         File file = new File( strPathFileNewsletterTemplate + File.separator + newsletterTemplate.getFileKey() );
-                        file.delete( );
+                        if( file.exists( ) ) {
+                            Files.delete( file.toPath( ) );
+                        }
                     }
                     newsletterTemplate.setFileKey( templateFileKey );
                 }
@@ -462,7 +465,9 @@ public String doModifyNewsletterTemplate( HttpServletRequest request )
                     {
                         String strPathFileNewsletterTemplate = AppPathService.getPath( PROPERTY_PATH_IMAGE_NEWSLETTER_TEMPLATE );
                         File file = new File( strPathFileNewsletterTemplate + File.separator + newsletterTemplate.getPictureKey() );
-                        file.delete( );
+                        if( file.exists( ) ) {
+                            Files.delete( file.toPath( ) );
+                        }
                     }
                     newsletterTemplate.setPictureKey( strImageKey );
                 }
@@ -536,7 +541,9 @@ public String getModifyNewsLetterTemplateFile( HttpServletRequest request )
                         fileWriter.close( );
                         fileReader = new BufferedReader( new FileReader( file ) );
                         // delete the temporary file
-                        file.delete( );
+                        if( file.exists( ) ) {
+                            Files.delete( file.toPath( ) );
+                        }
                         String strFileName = luteceTemplateFile.getTitle( );
                         model.put( NewsLetterConstants.MARK_TEMPLATE_FILE_NAME, strFileName );
                         model.put( fr.paris.lutece.plugins.newsletter.util.NewsLetterConstants.MARK_TEMPLATE_FILE, luteceTemplateFile.getPhysicalFile().getValue() );
@@ -641,7 +648,9 @@ public String doModifyNewsletterTemplateFile( HttpServletRequest request )
                     {
                         String strPathFileNewsletterTemplate = AppPathService.getPath( PROPERTY_PATH_IMAGE_NEWSLETTER_TEMPLATE );
                         File file = new File( strPathFileNewsletterTemplate + File.separator + strOldImageName );
-                        file.delete( );
+                        if( file.exists( ) ) {
+                            Files.delete(file.toPath());
+                        }
                     }
                 }
 
@@ -671,7 +680,9 @@ public String doModifyNewsletterTemplateFile( HttpServletRequest request )
                     luteceFile.setPhysicalFile( physicalFile );
                     String newFileKey =  NewsletterFileService.storeFile( luteceFile );
                     newsletterTemplate.setFileKey( newFileKey );
-                    file.delete();
+                    if( file.exists( ) ) {
+                        Files.delete( file.toPath( ) );
+                    }
 
                 }
 
@@ -756,30 +767,34 @@ public String doRemoveNewsLetterTemplate( HttpServletRequest request )
             return AdminMessageService.getMessageUrl( request, Messages.USER_ACCESS_DENIED, AdminMessage.TYPE_ERROR );
         }
 
-        String strFileName = newsLetterTemplate.getFileKey( );
-        String strPictureName = newsLetterTemplate.getPictureKey( );
+        try {
+            String strFileName = newsLetterTemplate.getFileKey( );
+            String strPictureName = newsLetterTemplate.getPictureKey( );
 
-        // removes the file
-        String strPathFileNewsletterTemplate = AppPathService.getPath( PROPERTY_PATH_TEMPLATE )
-                + AppPropertiesService.getProperty( NewsLetterConstants.PROPERTY_PATH_FILE_NEWSLETTER_TEMPLATE );
-        File file = new File( strPathFileNewsletterTemplate + NewsLetterConstants.CONSTANT_SLASH + strFileName );
+            // removes the file
+            String strPathFileNewsletterTemplate = AppPathService.getPath( PROPERTY_PATH_TEMPLATE )
+                    + AppPropertiesService.getProperty( NewsLetterConstants.PROPERTY_PATH_FILE_NEWSLETTER_TEMPLATE );
+            File file = new File( strPathFileNewsletterTemplate + NewsLetterConstants.CONSTANT_SLASH + strFileName );
 
-        if ( file.exists( ) )
-        {
-            file.delete( );
-        }
+            if ( file.exists( ) )
+            {
+                Files.delete( file.toPath( ) );
+            }
 
-        // removes the picture
-        String strPathImageNewsletterTemplate = AppPathService.getPath( PROPERTY_PATH_IMAGE_NEWSLETTER_TEMPLATE );
-        File picture = new File( strPathImageNewsletterTemplate + NewsLetterConstants.CONSTANT_SLASH + strPictureName );
+            // removes the picture
+            String strPathImageNewsletterTemplate = AppPathService.getPath( PROPERTY_PATH_IMAGE_NEWSLETTER_TEMPLATE );
+            File picture = new File( strPathImageNewsletterTemplate + NewsLetterConstants.CONSTANT_SLASH + strPictureName );
 
-        if ( picture.exists( ) )
-        {
-            picture.delete( );
-        }
+            if ( picture.exists( ) )
+            {
+                Files.delete( picture.toPath( ) );
+            }
 
-        // removes the newsletter template from the database
-        NewsLetterTemplateHome.remove( nNewsletterTemplateId, getPlugin( ) );
+            // removes the newsletter template from the database
+            NewsLetterTemplateHome.remove( nNewsletterTemplateId, getPlugin( ) );
+        } catch (IOException e) {
+            AppLogService.error( e.getMessage( ), e );
+        }
 
         // loads the newsletter templates management page
         // If the operation occurred well returns on the info of the newsletter