diff --git a/actionpack/lib/action_dispatch/journey/nodes/node.rb b/actionpack/lib/action_dispatch/journey/nodes/node.rb
index 4b7febfd20..c6f625beae 100644
--- a/actionpack/lib/action_dispatch/journey/nodes/node.rb
+++ b/actionpack/lib/action_dispatch/journey/nodes/node.rb
@@ -53,7 +53,7 @@ module ActionDispatch
               if formatted != false
                 # Add a constraint for wildcard route to make it non-greedy and
                 # match the optional format part of the route by default.
-                wildcard_options[node.name.to_sym] ||= /.+?/
+                wildcard_options[node.name.to_sym] ||= /.+?/m
               end
             end
 
diff --git a/actionpack/lib/action_dispatch/journey/route.rb b/actionpack/lib/action_dispatch/journey/route.rb
index 8c31307d48..1ce6ec243b 100644
--- a/actionpack/lib/action_dispatch/journey/route.rb
+++ b/actionpack/lib/action_dispatch/journey/route.rb
@@ -91,7 +91,8 @@ module ActionDispatch
       # as requirements.
       def requirements
         @defaults.merge(path.requirements).delete_if { |_, v|
-          /.+?/ == v
+          /.+?/ == v ||
+          /.+?/m == v
         }
       end
 
diff --git a/actionpack/lib/action_dispatch/routing/mapper.rb b/actionpack/lib/action_dispatch/routing/mapper.rb
index 3da6ab1e13..58d343eda5 100644
--- a/actionpack/lib/action_dispatch/routing/mapper.rb
+++ b/actionpack/lib/action_dispatch/routing/mapper.rb
@@ -146,7 +146,7 @@ module ActionDispatch
           end
 
           requirements, conditions = split_constraints ast.path_params, constraints
-          verify_regexp_requirements requirements.map(&:last).grep(Regexp)
+          verify_regexp_requirements requirements, ast.wildcard_options
 
           formats = normalize_format(formatted)
 
@@ -246,14 +246,18 @@ module ActionDispatch
             end
           end
 
-          def verify_regexp_requirements(requirements)
-            requirements.each do |requirement|
-              if ANCHOR_CHARACTERS_REGEX.match?(requirement.source)
+          def verify_regexp_requirements(requirements, wildcard_options)
+            requirements.each do |requirement, regex|
+              next unless regex.is_a? Regexp
+
+              if ANCHOR_CHARACTERS_REGEX.match?(regex.source)
                 raise ArgumentError, "Regexp anchor characters are not allowed in routing requirements: #{requirement.inspect}"
               end
 
-              if requirement.multiline?
-                raise ArgumentError, "Regexp multiline option is not allowed in routing requirements: #{requirement.inspect}"
+              if regex.multiline?
+                next if wildcard_options.key?(requirement)
+
+                raise ArgumentError, "Regexp multiline option is not allowed in routing requirements: #{regex.inspect}"
               end
             end
           end
diff --git a/actionpack/test/controller/routing_test.rb b/actionpack/test/controller/routing_test.rb
index 3912aa1a4d..ac10b8aa06 100644
--- a/actionpack/test/controller/routing_test.rb
+++ b/actionpack/test/controller/routing_test.rb
@@ -624,6 +624,34 @@ class LegacyRouteSetTests < ActiveSupport::TestCase
         url_for(rs, controller: "content", action: "show_file", path: %w(pages boo))
   end
 
+  def test_escapes_newline_character_for_dynamic_path
+    rs.draw do
+      get "/dynamic/:dynamic_segment" => "subpath_books#show", as: :dynamic
+
+      ActiveSupport::Deprecation.silence do
+        get ":controller/:action/:id"
+      end
+    end
+
+    results = rs.recognize_path("/dynamic/a%0Anewline")
+    assert(results, "Recognition should have succeeded")
+    assert_equal("a\nnewline", results[:dynamic_segment])
+  end
+
+  def test_escapes_newline_character_for_wildcard_path
+    rs.draw do
+      get "/wildcard/*wildcard_segment" => "subpath_books#show", as: :wildcard
+
+      ActiveSupport::Deprecation.silence do
+        get ":controller/:action/:id"
+      end
+    end
+
+    results = rs.recognize_path("/wildcard/a%0Anewline")
+    assert(results, "Recognition should have succeeded")
+    assert_equal("a\nnewline", results[:wildcard_segment])
+  end
+
   def test_dynamic_recall_paths_allowed
     rs.draw do
       get "*path" => "content#show_file"
diff --git a/actionpack/test/dispatch/mapper_test.rb b/actionpack/test/dispatch/mapper_test.rb
index 3f2841bae8..ed48b0e7ad 100644
--- a/actionpack/test/dispatch/mapper_test.rb
+++ b/actionpack/test/dispatch/mapper_test.rb
@@ -92,7 +92,7 @@ module ActionDispatch
         scope = Mapper::Scope.new({})
         ast = Journey::Parser.parse "/store/:name(*rest)"
         m = Mapper::Mapping.build(scope, FakeSet.new, ast, "foo", "bar", nil, [:get], nil, {}, true, options)
-        assert_equal(/.+?/, m.requirements[:rest])
+        assert_equal(/.+?/m, m.requirements[:rest])
       end
 
       def test_via_scope
@@ -137,7 +137,7 @@ module ActionDispatch
         mapper = Mapper.new fakeset
         mapper.get "/*path", to: "pages#show"
         assert_equal "/*path(.:format)", fakeset.asts.first.to_s
-        assert_equal(/.+?/, fakeset.requirements.first[:path])
+        assert_equal(/.+?/m, fakeset.requirements.first[:path])
       end
 
       def test_map_wildcard_with_other_element
@@ -145,7 +145,7 @@ module ActionDispatch
         mapper = Mapper.new fakeset
         mapper.get "/*path/foo/:bar", to: "pages#show"
         assert_equal "/*path/foo/:bar(.:format)", fakeset.asts.first.to_s
-        assert_equal(/.+?/, fakeset.requirements.first[:path])
+        assert_equal(/.+?/m, fakeset.requirements.first[:path])
       end
 
       def test_map_wildcard_with_multiple_wildcard
@@ -153,8 +153,8 @@ module ActionDispatch
         mapper = Mapper.new fakeset
         mapper.get "/*foo/*bar", to: "pages#show"
         assert_equal "/*foo/*bar(.:format)", fakeset.asts.first.to_s
-        assert_equal(/.+?/, fakeset.requirements.first[:foo])
-        assert_equal(/.+?/, fakeset.requirements.first[:bar])
+        assert_equal(/.+?/m, fakeset.requirements.first[:foo])
+        assert_equal(/.+?/m, fakeset.requirements.first[:bar])
       end
 
       def test_map_wildcard_with_format_false
diff --git a/actionpack/test/dispatch/routing/route_set_test.rb b/actionpack/test/dispatch/routing/route_set_test.rb
index 0247b90c5a..d7b611b664 100644
--- a/actionpack/test/dispatch/routing/route_set_test.rb
+++ b/actionpack/test/dispatch/routing/route_set_test.rb
@@ -149,6 +149,22 @@ module ActionDispatch
         assert_equal "/users/1.json", url_helpers.user_path(1, :json)
       end
 
+      test "escape new line for dynamic params" do
+        draw do
+          get "/dynamic/:dynamic_segment", to: SimpleApp.new("foo#index"), as: :dynamic
+        end
+
+        assert_equal "/dynamic/a%0Anewline", url_helpers.dynamic_path(dynamic_segment: "a\nnewline")
+      end
+
+      test "escape new line for wildcard params" do
+        draw do
+          get "/wildcard/*wildcard_segment", to: SimpleApp.new("foo#index"), as: :wildcard
+        end
+
+        assert_equal "/wildcard/a%0Anewline", url_helpers.wildcard_path(wildcard_segment: "a\nnewline")
+      end
+
       private
         def draw(&block)
           @set.draw(&block)
diff --git a/actionpack/test/journey/nodes/ast_test.rb b/actionpack/test/journey/nodes/ast_test.rb
index 2bfcfcc87e..b809c80b6f 100644
--- a/actionpack/test/journey/nodes/ast_test.rb
+++ b/actionpack/test/journey/nodes/ast_test.rb
@@ -67,7 +67,7 @@ module ActionDispatch
           ast = Ast.new(tree, true)
 
           wildcard_options = ast.wildcard_options
-          assert_equal %r{.+?}, wildcard_options[:glob]
+          assert_equal %r{.+?}m, wildcard_options[:glob]
         end
 
         def test_wildcard_options_when_false
@@ -83,7 +83,7 @@ module ActionDispatch
           ast = Ast.new(tree, nil)
 
           wildcard_options = ast.wildcard_options
-          assert_equal %r{.+?}, wildcard_options[:glob]
+          assert_equal %r{.+?}m, wildcard_options[:glob]
         end
       end
     end