diff --git a/Gemfile.lock b/Gemfile.lock
index d737253219d25..3b29cd668731a 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -9,7 +9,7 @@ GEM
     nokogiri (1.3.3)
     pg (0.9.0)
     rack (1.1.0)
-    railslts-version (2.3.18.6)
+    railslts-version (2.3.18.8)
     rake (0.8.7)
     rdoc (2.5.11)
     sqlite3 (1.3.7)
diff --git a/actionpack/lib/action_view/helpers/number_helper.rb b/actionpack/lib/action_view/helpers/number_helper.rb
index 788c459e2ef91..37f6b3ac21162 100644
--- a/actionpack/lib/action_view/helpers/number_helper.rb
+++ b/actionpack/lib/action_view/helpers/number_helper.rb
@@ -83,7 +83,7 @@ def number_to_currency(number, options = {})
         unit      = options[:unit]      || defaults[:unit]
         separator = options[:separator] || defaults[:separator]
         delimiter = options[:delimiter] || defaults[:delimiter]
-        format    = options[:format]    || defaults[:format]
+        format    = options[:format] ? ERB::Util.html_escape(options[:format]) : defaults[:format]
         separator = '' if precision == 0
 
         begin
diff --git a/actionpack/test/template/number_helper_test.rb b/actionpack/test/template/number_helper_test.rb
index 4263613a9c3c6..fcf4b4ba4fa19 100644
--- a/actionpack/test/template/number_helper_test.rb
+++ b/actionpack/test/template/number_helper_test.rb
@@ -3,6 +3,28 @@
 class NumberHelperTest < ActionView::TestCase
   tests ActionView::Helpers::NumberHelper
 
+
+  def test_number_helpers_escape_delimiter_and_separator
+    # html-escaping the right side is fine, since we only have a problem if the helper does
+    # not escape AND return a safe string
+
+    assert_equal "111&lt;script&gt;&lt;/script&gt;111&lt;script&gt;&lt;/script&gt;1111", ERB::Util.html_escape(number_to_phone(1111111111, :delimiter => "<script></script>"))
+
+    assert_equal "$1&lt;script&gt;&lt;/script&gt;01", ERB::Util.html_escape(number_to_currency(1.01, :separator => "<script></script>"))
+    assert_equal "$1&lt;script&gt;&lt;/script&gt;000.00", ERB::Util.html_escape(number_to_currency(1000, :delimiter => "<script></script>"))
+
+    assert_equal "1&lt;script&gt;&lt;/script&gt;010%", ERB::Util.html_escape(number_to_percentage(1.01, :separator => "<script></script>"))
+    assert_equal "1&lt;script&gt;&lt;/script&gt;000.000%", ERB::Util.html_escape(number_to_percentage(1000, :delimiter => "<script></script>"))
+
+    assert_equal "1&lt;script&gt;&lt;/script&gt;01", ERB::Util.html_escape(number_with_delimiter(1.01, :separator => "<script></script>"))
+    assert_equal "1&lt;script&gt;&lt;/script&gt;000", ERB::Util.html_escape(number_with_delimiter(1000, :delimiter => "<script></script>"))
+
+    assert_equal "1&lt;script&gt;&lt;/script&gt;010", ERB::Util.html_escape(number_with_precision(1.01, :separator => "<script></script>"))
+    assert_equal "1&lt;script&gt;&lt;/script&gt;000.000", ERB::Util.html_escape(number_with_precision(1000, :delimiter => "<script></script>"))
+
+    assert_equal "9&lt;script&gt;&lt;/script&gt;9 KB", ERB::Util.html_escape(number_to_human_size(10100, :separator => "<script></script>"))
+  end
+
   def test_number_to_phone
     assert_equal("555-1234", number_to_phone(5551234))
     assert_equal("800-555-1212", number_to_phone(8005551212))
@@ -15,6 +37,8 @@ def test_number_to_phone
     assert_equal("+18005551212", number_to_phone(8005551212, :country_code => 1, :delimiter => ''))
     assert_equal("22-555-1212", number_to_phone(225551212))
     assert_equal("+45-22-555-1212", number_to_phone(225551212, :country_code => 45))
+    assert_equal "+&lt;script&gt;&lt;/script&gt;8005551212", ERB::Util.html_escape(number_to_phone(8005551212, :country_code => "<script></script>", :delimiter => ""))
+    assert_equal "8005551212 x &lt;script&gt;&lt;/script&gt;", ERB::Util.html_escape(number_to_phone(8005551212, :extension => "<script></script>", :delimiter => ""))
     assert_equal("x", number_to_phone("x"))
     assert_nil number_to_phone(nil)
   end
@@ -28,6 +52,7 @@ def test_number_to_currency
     assert_equal("&amp;pound;1234567890,50", number_to_currency(1234567890.50, {:unit => "&pound;", :separator => ",", :delimiter => ""}))
     assert_equal("$1,234,567,890.50", number_to_currency("1234567890.50"))
     assert_equal("1,234,567,890.50 K&#269;", number_to_currency("1234567890.50", {:unit => raw("K&#269;"), :format => "%n %u"}))
+    assert_equal "&lt;b&gt;1,234,567,890.50&lt;/b&gt; $", ERB::Util.html_escape(number_to_currency("1234567890.50", :format => "<b>%n</b> %u"))
     #assert_equal("$x.", number_to_currency("x")) # fails due to API consolidation
     assert_equal("$x", number_to_currency("x"))
     assert_nil number_to_currency(nil)
diff --git a/railties/railties.gemspec b/railties/railties.gemspec
index 6e780108ca1d1..ccbde9872ed90 100644
--- a/railties/railties.gemspec
+++ b/railties/railties.gemspec
@@ -19,5 +19,5 @@ Gem::Specification.new do |s|
   s.add_dependency 'actionpack',     '= 2.3.18'
   s.add_dependency 'actionmailer',   '= 2.3.18'
   s.add_dependency 'activeresource', '= 2.3.18'
-  s.add_dependency 'railslts-version', '= 2.3.18.7'
+  s.add_dependency 'railslts-version', '= 2.3.18.8'
 end