diff --git a/mozilla/webtools/bugzilla/.bzrrev b/mozilla/webtools/bugzilla/.bzrrev
index 0659a4cb18f..23278b8408b 100644
--- a/mozilla/webtools/bugzilla/.bzrrev
+++ b/mozilla/webtools/bugzilla/.bzrrev
@@ -1 +1 @@
-8009
\ No newline at end of file
+8010
\ No newline at end of file
diff --git a/mozilla/webtools/bugzilla/Bugzilla/CGI.pm b/mozilla/webtools/bugzilla/Bugzilla/CGI.pm
index e0e1c40ba33..9d8a1c48ffc 100644
--- a/mozilla/webtools/bugzilla/Bugzilla/CGI.pm
+++ b/mozilla/webtools/bugzilla/Bugzilla/CGI.pm
@@ -306,6 +306,10 @@ sub header {
         unshift(@_, '-x_frame_options' => 'SAMEORIGIN');
     }
 
+    # Add X-XSS-Protection header to prevent simple XSS attacks
+    # and enforce the blocking (rather than the rewriting) mode.
+    unshift(@_, '-x_xss_protection' => '1; mode=block');
+
     return $self->SUPER::header(@_) || "";
 }