Escapes milestone and label names when promoting them

app/controllers/projects/labels_controller.rb

@@ -112,7 +112,7 @@ class Projects::LabelsController < Projects::ApplicationController
     begin
       return render_404 unless promote_service.execute(@label)
 
-      flash[:notice] = "#{@label.title} promoted to <a href=\"#{group_labels_path(@project.group)}\">group label</a>.".html_safe
+      flash[:notice] = flash_notice_for(@label, @project.group)
       respond_to do |format|
         format.html do
           redirect_to(project_labels_path(@project), status: :see_other)
@@ -135,6 +135,15 @@ class Projects::LabelsController < Projects::ApplicationController
     end
   end
 
+  def flash_notice_for(label, group)
+    notice = ''.html_safe
+    notice << label.title
+    notice << ' promoted to '
+    notice << view_context.link_to('<u>group label</u>'.html_safe, group_labels_path(group))
+    notice << '.'
+    notice
+  end
+
   protected
 
   def label_params

app/controllers/projects/milestones_controller.rb

@@ -1,5 +1,4 @@
 class Projects::MilestonesController < Projects::ApplicationController
-  include ActionView::Helpers::SanitizeHelper
   include Gitlab::Utils::StrongMemoize
   include MilestoneActions
 
@@ -77,8 +76,8 @@ class Projects::MilestonesController < Projects::ApplicationController
 
   def promote
     promoted_milestone = Milestones::PromoteService.new(project, current_user).execute(milestone)
-    milestone_title = sanitize(milestone.title)
-    flash[:notice] = "#{milestone_title} promoted to <a href=\"#{group_milestone_path(project.group, promoted_milestone.iid)}\"><u>group milestone</u></a>.".html_safe
+    flash[:notice] = flash_notice_for(promoted_milestone, project.group)
+
     respond_to do |format|
       format.html do
         redirect_to project_milestones_path(project)
@@ -91,6 +90,15 @@ class Projects::MilestonesController < Projects::ApplicationController
     redirect_to milestone, alert: error.message
   end
 
+  def flash_notice_for(milestone, group)
+    notice = ''.html_safe
+    notice << milestone.title
+    notice << ' promoted to '
+    notice << view_context.link_to('<u>group milestone</u>'.html_safe, group_milestone_path(group, milestone.iid))
+    notice << '.'
+    notice
+  end
+
   def destroy
     return access_denied! unless can?(current_user, :admin_milestone, @project)
 

spec/controllers/projects/labels_controller_spec.rb

@@ -143,6 +143,14 @@ describe Projects::LabelsController do
         expect(GroupLabel.find_by(title: promoted_label_name)).not_to be_nil
       end
 
+      it 'renders label name without parsing it as HTML' do
+        label_1.update!(name: 'CCC<img src=x onerror=alert(document.domain)>')
+
+        post :promote, namespace_id: project.namespace.to_param, project_id: project, id: label_1.to_param
+
+        expect(flash[:notice]).to eq("CCC&lt;img src=x onerror=alert(document.domain)&gt; promoted to <a href=\"#{group_labels_path(project.group)}\"><u>group label</u></a>.")
+      end
+
       context 'service raising InvalidRecord' do
         before do
           expect_any_instance_of(Labels::PromoteService).to receive(:execute) do |label|

spec/controllers/projects/milestones_controller_spec.rb

@@ -133,7 +133,7 @@ describe Projects::MilestonesController do
 
         post :promote, namespace_id: project.namespace.id, project_id: project.id, id: milestone.iid
 
-        expect(flash[:notice]).to eq("CCC<img src=\"x\"> promoted to <a href=\"#{group_milestone_path(project.group, milestone.iid)}\"><u>group milestone</u></a>.")
+        expect(flash[:notice]).to eq("CCC promoted to <a href=\"#{group_milestone_path(project.group, milestone.iid)}\"><u>group milestone</u></a>.")
       end
     end