Bug 968576: [SECURITY] Dangerous control characters allowed in Bugzilla text

Bugzilla/Template.pm

@@ -645,6 +645,17 @@ sub create {
                 my ($data) = @_;
                 return encode_base64($data);
             },
+
+            # Strips out control characters excepting whitespace
+            strip_control_chars => sub {
+                my ($data) = @_;
+                # Only run for utf8 to avoid issues with other multibyte encodings 
+                # that may be reassigning meaning to ascii characters.
+                if (Bugzilla->params->{'utf8'}) {
+                    $data =~ s/(?![\t\r\n])[[:cntrl:]]//g;
+                }
+                return $data;
+            },
             
             # HTML collapses newlines in element attributes to a single space,
             # so form elements which may have whitespace (ie comments) need

Bugzilla/Util.pm

@@ -68,6 +68,10 @@ sub html_quote {
     # Obscure '@'.
     $var =~ s/\@/\@/g;
     if (Bugzilla->params->{'utf8'}) {
+        # Remove control characters if the encoding is utf8.
+        # Other multibyte encodings may be using this range; so ignore if not utf8.
+        $var =~ s/(?![\t\r\n])[[:cntrl:]]//g;
+
         # Remove the following characters because they're
         # influencing BiDi:
         # --------------------------------------------------------

template/en/default/email/bugmail.txt.tmpl

@@ -19,7 +19,7 @@
 [%- IF comment.count %]
 --- Comment #[% comment.count %] from [% comment.author.identity %] ---
 [% END %]
-[%+ comment.body_full({ is_bugmail => 1, wrap => 1 }) %]
+[%+ comment.body_full({ is_bugmail => 1, wrap => 1 }) FILTER strip_control_chars %]
 [% END %]
 
 -- [%# Protect the trailing space of the signature marker %]

template/en/default/email/flagmail.txt.tmpl

@@ -68,7 +68,7 @@ Attachment [% attidsummary %]
 [%-# .defined is necessary to avoid a taint issue in Perl < 5.10.1, see bug 509794. %]
 [% IF Bugzilla.cgi.param("comment").defined && Bugzilla.cgi.param("comment").length > 0 %]
 ------- Additional Comments from [% user.identity %]
-[%+ Bugzilla.cgi.param("comment") %]
+[%+ Bugzilla.cgi.param("comment") FILTER strip_control_chars %]
 [% END %]
 
 [%- END %]