diff --git a/app/assets/javascripts/api.js b/app/assets/javascripts/api.js
index 1cd2302111e..7e5e9fa9ae5 100644
--- a/app/assets/javascripts/api.js
+++ b/app/assets/javascripts/api.js
@@ -5,7 +5,7 @@
     namespacesPath: "/api/:version/namespaces.json",
     groupProjectsPath: "/api/:version/groups/:id/projects.json",
     projectsPath: "/api/:version/projects.json?simple=true",
-    labelsPath: "/api/:version/projects/:id/labels",
+    labelsPath: "/:namespace_path/:project_path/labels",
     licensePath: "/api/:version/licenses/:key",
     gitignorePath: "/api/:version/gitignores/:key",
     gitlabCiYmlPath: "/api/:version/gitlab_ci_ymls/:key",
@@ -65,13 +65,14 @@
         return callback(projects);
       });
     },
-    newLabel: function(project_id, data, callback) {
+    newLabel: function(namespace_path, project_path, data, callback) {
       var url = Api.buildUrl(Api.labelsPath)
-        .replace(':id', project_id);
+        .replace(':namespace_path', namespace_path)
+        .replace(':project_path', project_path);
       return $.ajax({
         url: url,
         type: "POST",
-        data: data,
+        data: {'label': data},
         dataType: "json"
       }).done(function(label) {
         return callback(label);
diff --git a/app/assets/javascripts/boards/components/new_list_dropdown.js.es6 b/app/assets/javascripts/boards/components/new_list_dropdown.js.es6
index 1a4d8157970..6ccd83e2d84 100644
--- a/app/assets/javascripts/boards/components/new_list_dropdown.js.es6
+++ b/app/assets/javascripts/boards/components/new_list_dropdown.js.es6
@@ -3,8 +3,7 @@ $(() => {
 
   $('.js-new-board-list').each(function () {
     const $this = $(this);
-
-    new gl.CreateLabelDropdown($this.closest('.dropdown').find('.dropdown-new-label'), $this.data('project-id'));
+    new gl.CreateLabelDropdown($this.closest('.dropdown').find('.dropdown-new-label'), $this.data('namespace-path'), $this.data('project-path'));
 
     $this.glDropdown({
       data(term, callback) {
diff --git a/app/assets/javascripts/create_label.js.es6 b/app/assets/javascripts/create_label.js.es6
index 46d1c3f00c1..c5f8c29242d 100644
--- a/app/assets/javascripts/create_label.js.es6
+++ b/app/assets/javascripts/create_label.js.es6
@@ -1,8 +1,9 @@
 (function (w) {
   class CreateLabelDropdown {
-    constructor ($el, projectId) {
+    constructor ($el, namespacePath, projectPath) {
       this.$el = $el;
-      this.projectId = projectId;
+      this.namespacePath = namespacePath;
+      this.projectPath = projectPath;
       this.$dropdownBack = $('.dropdown-menu-back', this.$el.closest('.dropdown'));
       this.$cancelButton = $('.js-cancel-label-btn', this.$el);
       this.$newLabelField = $('#new_label_name', this.$el);
@@ -91,8 +92,8 @@
       e.preventDefault();
       e.stopPropagation();
 
-      Api.newLabel(this.projectId, {
-        name: this.$newLabelField.val(),
+      Api.newLabel(this.namespacePath, this.projectPath, {
+        title: this.$newLabelField.val(),
         color: this.$newColorField.val()
       }, (label) => {
         this.$newLabelCreateButton.enable();
diff --git a/app/assets/javascripts/labels_select.js b/app/assets/javascripts/labels_select.js
index 3f15a117ca8..51a84066185 100644
--- a/app/assets/javascripts/labels_select.js
+++ b/app/assets/javascripts/labels_select.js
@@ -4,9 +4,10 @@
       var _this;
       _this = this;
       $('.js-label-select').each(function(i, dropdown) {
-        var $block, $colorPreview, $dropdown, $form, $loading, $selectbox, $sidebarCollapsedValue, $value, abilityName, defaultLabel, enableLabelCreateButton, issueURLSplit, issueUpdateURL, labelHTMLTemplate, labelNoneHTMLTemplate, labelUrl, projectId, saveLabelData, selectedLabel, showAny, showNo, $sidebarLabelTooltip;
+        var $block, $colorPreview, $dropdown, $form, $loading, $selectbox, $sidebarCollapsedValue, $value, abilityName, defaultLabel, enableLabelCreateButton, issueURLSplit, issueUpdateURL, labelHTMLTemplate, labelNoneHTMLTemplate, labelUrl, namespacePath, projectPath, saveLabelData, selectedLabel, showAny, showNo, $sidebarLabelTooltip;
         $dropdown = $(dropdown);
-        projectId = $dropdown.data('project-id');
+        namespacePath = $dropdown.data('namespace-path');
+        projectPath = $dropdown.data('project-path');
         labelUrl = $dropdown.data('labels');
         issueUpdateURL = $dropdown.data('issueUpdate');
         selectedLabel = $dropdown.data('selected');
@@ -35,7 +36,7 @@
         $sidebarLabelTooltip.tooltip();
 
         if ($dropdown.closest('.dropdown').find('.dropdown-new-label').length) {
-          new gl.CreateLabelDropdown($dropdown.closest('.dropdown').find('.dropdown-new-label'), projectId);
+          new gl.CreateLabelDropdown($dropdown.closest('.dropdown').find('.dropdown-new-label'), namespacePath, projectPath);
         }
 
         saveLabelData = function() {
diff --git a/app/controllers/projects/labels_controller.rb b/app/controllers/projects/labels_controller.rb
index 28fa4a5b141..a6626df4826 100644
--- a/app/controllers/projects/labels_controller.rb
+++ b/app/controllers/projects/labels_controller.rb
@@ -30,9 +30,15 @@ class Projects::LabelsController < Projects::ApplicationController
     @label = @project.labels.create(label_params)
 
     if @label.valid?
-      redirect_to namespace_project_labels_path(@project.namespace, @project)
+      respond_to do |format|
+        format.html { redirect_to namespace_project_labels_path(@project.namespace, @project) }
+        format.json { render json: @label }
+      end
     else
-      render 'new'
+      respond_to do |format|
+        format.html { render 'new' }
+        format.json { render json: { message: @label.errors.messages }, status: 400 }
+      end
     end
   end
 
diff --git a/app/views/shared/issuable/_filter.html.haml b/app/views/shared/issuable/_filter.html.haml
index cf26197f7d7..f17096968f6 100644
--- a/app/views/shared/issuable/_filter.html.haml
+++ b/app/views/shared/issuable/_filter.html.haml
@@ -37,7 +37,7 @@
               %input.pull-left.form-control{ type: "search", placeholder: "Filter by name...", "v-model" => "filters.search", "debounce" => "250" }
               - if can?(current_user, :admin_list, @project)
                 .dropdown.pull-right
-                  %button.btn.btn-create.js-new-board-list{ type: "button", data: { toggle: "dropdown", labels: labels_filter_path, project_id: @project.try(:id) } }
+                  %button.btn.btn-create.js-new-board-list{ type: "button", data: { toggle: "dropdown", labels: labels_filter_path, namespace_path: @project.try(:namespace).try(:path), project_path: @project.try(:path) } }
                     Create new list
                   .dropdown-menu.dropdown-menu-paging.dropdown-menu-align-right.dropdown-menu-issues-board-new.dropdown-menu-selectable
                     = render partial: "shared/issuable/label_page_default", locals: { show_footer: true, show_create: true, show_boards_content: true, title: "Create a new list" }
diff --git a/app/views/shared/issuable/_label_dropdown.html.haml b/app/views/shared/issuable/_label_dropdown.html.haml
index d34d28f6736..ebe441c931e 100644
--- a/app/views/shared/issuable/_label_dropdown.html.haml
+++ b/app/views/shared/issuable/_label_dropdown.html.haml
@@ -4,7 +4,7 @@
 - show_footer = local_assigns.fetch(:show_footer, true)
 - data_options = local_assigns.fetch(:data_options, {})
 - classes = local_assigns.fetch(:classes, [])
-- dropdown_data = {toggle: 'dropdown', field_name: 'label_name[]', show_no: "true", show_any: "true", selected: params[:label_name], project_id: @project.try(:id), labels: labels_filter_path, default_label: "Label"}
+- dropdown_data = {toggle: 'dropdown', field_name: 'label_name[]', show_no: "true", show_any: "true", selected: params[:label_name], namespace_path: @project.try(:namespace).try(:path), project_path: @project.try(:path), labels: labels_filter_path, default_label: "Label"}
 - dropdown_data.merge!(data_options)
 - classes << 'js-extra-options' if extra_options
 - classes << 'js-filter-submit' if filter_submit
diff --git a/app/views/shared/issuable/_sidebar.html.haml b/app/views/shared/issuable/_sidebar.html.haml
index b13daaf43c9..0464ebddc11 100644
--- a/app/views/shared/issuable/_sidebar.html.haml
+++ b/app/views/shared/issuable/_sidebar.html.haml
@@ -128,7 +128,7 @@
             - issuable.labels_array.each do |label|
               = hidden_field_tag "#{issuable.to_ability_name}[label_names][]", label.id, id: nil
             .dropdown
-              %button.dropdown-menu-toggle.js-label-select.js-multiselect{type: "button", data: {toggle: "dropdown", field_name: "#{issuable.to_ability_name}[label_names][]", ability_name: issuable.to_ability_name, show_no: "true", show_any: "true", project_id: (@project.id if @project), issue_update: issuable_json_path(issuable), labels: (namespace_project_labels_path(@project.namespace, @project, :json) if @project)}}
+              %button.dropdown-menu-toggle.js-label-select.js-multiselect{type: "button", data: {toggle: "dropdown", field_name: "#{issuable.to_ability_name}[label_names][]", ability_name: issuable.to_ability_name, show_no: "true", show_any: "true", namespace_path: @project.try(:namespace).try(:path), project_path: @project.try(:path), issue_update: issuable_json_path(issuable), labels: (namespace_project_labels_path(@project.namespace, @project, :json) if @project)}}
                 %span.dropdown-toggle-text
                   Label
                 = icon('chevron-down')
diff --git a/lib/api/helpers.rb b/lib/api/helpers.rb
index 714d4ea3dc6..8b8c4eb4d46 100644
--- a/lib/api/helpers.rb
+++ b/lib/api/helpers.rb
@@ -21,8 +21,11 @@ module API
     end
 
     # Check the Rails session for valid authentication details
+    #
+    # Until CSRF protection is added to the API, disallow this method for
+    # state-changing endpoints
     def find_user_from_warden
-      warden ? warden.authenticate : nil
+      warden.try(:authenticate) if request.get? || request.head?
     end
 
     def find_user_by_private_token
diff --git a/spec/requests/api/api_helpers_spec.rb b/spec/requests/api/api_helpers_spec.rb
index e66faeed705..0f41f8dc7f1 100644
--- a/spec/requests/api/api_helpers_spec.rb
+++ b/spec/requests/api/api_helpers_spec.rb
@@ -10,7 +10,8 @@ describe API::Helpers, api: true do
   let(:key) { create(:key, user: user) }
 
   let(:params) { {} }
-  let(:env) { {} }
+  let(:env) { { 'REQUEST_METHOD' => 'GET' } }
+  let(:request) { Rack::Request.new(env) }
 
   def set_env(token_usr, identifier)
     clear_env
@@ -52,17 +53,43 @@ describe API::Helpers, api: true do
   describe ".current_user" do
     subject { current_user }
 
-    describe "when authenticating via Warden" do
+    describe "Warden authentication" do
       before { doorkeeper_guard_returns false }
 
-      context "fails" do
-        it { is_expected.to be_nil }
+      context "with invalid credentials" do
+        context "GET request" do
+          before { env['REQUEST_METHOD'] = 'GET' }
+          it { is_expected.to be_nil }
+        end
       end
 
-      context "succeeds" do
+      context "with valid credentials" do
         before { warden_authenticate_returns user }
 
-        it { is_expected.to eq(user) }
+        context "GET request" do
+          before { env['REQUEST_METHOD'] = 'GET' }
+          it { is_expected.to eq(user) }
+        end
+
+        context "HEAD request" do
+          before { env['REQUEST_METHOD'] = 'HEAD' }
+          it { is_expected.to eq(user) }
+        end
+
+        context "PUT request" do
+          before { env['REQUEST_METHOD'] = 'PUT' }
+          it { is_expected.to be_nil }
+        end
+
+        context "POST request" do
+          before { env['REQUEST_METHOD'] = 'POST' }
+          it { is_expected.to be_nil }
+        end
+
+        context "DELETE request" do
+          before { env['REQUEST_METHOD'] = 'DELETE' }
+          it { is_expected.to be_nil }
+        end
       end
     end