Escape the unit value provided to number_to_currency

Previously the unit values were trusted leading to potential XSS vulnerabilities.

Fixes: CVE-2013-6415

actionview/lib/action_view/helpers/number_helper.rb

@@ -394,6 +394,7 @@ def delegate_number_helper_method(method, number, options)
       def escape_unsafe_delimiters_and_separators(options)
         options[:separator] = ERB::Util.html_escape(options[:separator]) if options[:separator] && !options[:separator].html_safe?
         options[:delimiter] = ERB::Util.html_escape(options[:delimiter]) if options[:delimiter] && !options[:delimiter].html_safe?
+        options[:unit]      = ERB::Util.html_escape(options[:unit]) if options[:unit] && !options[:unit].html_safe?
         options
       end
 

actionview/test/template/number_helper_test.rb

@@ -14,7 +14,8 @@ def test_number_to_currency
     assert_equal nil, number_to_currency(nil)
     assert_equal "$1,234,567,890.50", number_to_currency(1234567890.50)
     assert_equal "$1,234,567,892", number_to_currency(1234567891.50, precision: 0)
-    assert_equal "1,234,567,890.50 - Kč", number_to_currency("-1234567890.50", unit: "Kč", format: "%n %u", negative_format: "%n - %u")
+    assert_equal "1,234,567,890.50 - Kč", number_to_currency("-1234567890.50", unit: raw("Kč"), format: "%n %u", negative_format: "%n - %u")
+    assert_equal "£1,234,567,890.50", number_to_currency("1234567890.50", unit: "£")
   end
 
   def test_number_to_percentage