diff --git a/app/controllers/topics_controller.rb b/app/controllers/topics_controller.rb
index b5d910a8259..aca86dd57c0 100644
--- a/app/controllers/topics_controller.rb
+++ b/app/controllers/topics_controller.rb
@@ -51,6 +51,10 @@ class TopicsController < ApplicationController
   end
 
   def show
+    if params[:id].is_a?(Array)
+      raise Discourse::InvalidParameters.new("Show only accepts a single ID")
+    end
+
     flash["referer"] ||= request.referer[0..255] if request.referer
 
     # TODO: We'd like to migrate the wordpress feed to another url. This keeps up backwards
diff --git a/spec/requests/topics_controller_spec.rb b/spec/requests/topics_controller_spec.rb
index 66af5a01982..94eed15ed3b 100644
--- a/spec/requests/topics_controller_spec.rb
+++ b/spec/requests/topics_controller_spec.rb
@@ -2322,6 +2322,12 @@ RSpec.describe TopicsController do
       expect(response).to redirect_to(topic.relative_url)
     end
 
+    it "does not raise an unhandled exception when receiving an array of IDs" do
+      get "/t/#{topic.id}/summary?id[]=a,b"
+
+      expect(response.status).to eq(400)
+    end
+
     it "keeps the post_number parameter around when redirecting" do
       get "/t/#{topic.slug}", params: { post_number: 42 }
       expect(response).to redirect_to(topic.relative_url + "/42")