--- lib/cgi.rb  (revision 19665)
+++ lib/cgi.rb  (working copy)
@@ -546,6 +546,11 @@
     when Hash
       options = options.dup
     end
+    options.each_value do |value|
+      if /\n(?![ \t])/ === value
+        raise ArgumentError, "potential HTTP header injection detected"
+      end
+    end

     unless options.has_key?("type")
       options["type"] = "text/html"