diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index a3eaec4bb..83b30d45d 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -511,11 +511,9 @@ class ApplicationController < ActionController::Base
         if uri.send(component).present? && uri.send(component) != request.send(component)
           return false
         end
-
-        uri.send(:"#{component}=", nil)
       end
-      # Always ignore basic user:password in the URL
-      uri.userinfo = nil
+      # Remove unnecessary components to convert the URL into a relative URL
+      uri.omit!(:scheme, :userinfo, :host, :port)
     rescue Addressable::URI::InvalidURIError
       return false
     end
diff --git a/test/functional/account_controller_test.rb b/test/functional/account_controller_test.rb
index e62dce943..31ba88fb5 100644
--- a/test/functional/account_controller_test.rb
+++ b/test/functional/account_controller_test.rb
@@ -658,4 +658,22 @@ class AccountControllerTest < Redmine::ControllerTest
       end
     end
   end
+
+  def test_validate_back_url
+    request.host = 'example.com'
+
+    assert_equal '/admin', @controller.send(:validate_back_url, 'http://example.com/admin')
+    assert_equal '/admin', @controller.send(:validate_back_url, 'http://dlopper:foo@example.com/admin')
+    assert_equal '/issues?query_id=1#top', @controller.send(:validate_back_url, 'http://example.com/issues?query_id=1#top')
+    assert_equal false, @controller.send(:validate_back_url, 'http://invalid.example.com/issues')
+  end
+
+  def test_validate_back_url_with_port
+    request.host = 'example.com:3000'
+
+    assert_equal '/admin', @controller.send(:validate_back_url, 'http://example.com:3000/admin')
+    assert_equal '/admin', @controller.send(:validate_back_url, 'http://dlopper:foo@example.com:3000/admin')
+    assert_equal '/issues?query_id=1#top', @controller.send(:validate_back_url, 'http://example.com:3000/issues?query_id=1#top')
+    assert_equal false, @controller.send(:validate_back_url, 'http://invalid.example.com:3000/issues')
+  end
 end