Bug 1031035: xmlrpc can be DoS'd with billion laughs attack

Bugzilla/WebService/Server/XMLRPC.pm

@@ -131,6 +131,14 @@ use Bugzilla::WebService::Constants qw(XMLRPC_CONTENT_TYPE_WHITELIST);
 use Bugzilla::WebService::Util qw(fix_credentials);
 use Scalar::Util qw(tainted);
 
+sub new {
+    my $self = shift->SUPER::new(@_);
+    # Initialise XML::Parser to not expand references to entities, to prevent DoS
+    require XML::Parser;
+    $self->{_parser}->parser(parser => XML::Parser->new( NoExpand => 1, Handlers => { Default => sub {} } ));
+    return $self;
+}
+
 sub deserialize {
     my $self = shift;
 

importxml.pl

@@ -1275,6 +1275,9 @@ my $twig = XML::Twig->new(
     },
     start_tag_handlers => { bugzilla => \&init }
 );
+# Prevent DoS using the billion laughs attack.
+$twig->{NoExpand} = 1;
+
 $twig->parse($xml);
 my $root       = $twig->root;
 my $maintainer = $root->{'att'}->{'maintainer'};