--- loncom/lonnet/perl/londns.pm	2013/09/02 14:40:18	1.3
+++ loncom/lonnet/perl/londns.pm	2017/11/30 14:33:35	1.4
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # A debugging harness.
 #
-# $Id: londns.pm,v 1.3 2013/09/02 14:40:18 raeburn Exp $
+# $Id: londns.pm,v 1.4 2017/11/30 14:33:35 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -36,13 +36,16 @@ use Apache::lonnet;
 
 sub serve_file {
     my ($r,$file,$type)=@_;
-    open(my $config,"<$Apache::lonnet::perlvar{'lonTabDir'}/$file");
-    my $file = join('',<$config>);
-    $r->content_type($type);
-    $r->send_http_header;
-    return OK if $r->header_only;
-    $r->print($file);
-    return OK;
+    if (open(my $config,"<","$Apache::lonnet::perlvar{'lonTabDir'}/$file")) {
+        my $contents = join('',<$config>);
+        $r->content_type($type);
+        $r->send_http_header;
+        return OK if $r->header_only;
+        $r->print($contents);
+        return OK;
+    } else {
+        return FORBIDDEN;
+    }
 }
 
 sub handler {