SECURITY: Fix XSS in calendar event name (#607)

We need to sanitize event names to prevent XSS from occurring in events.

assets/javascripts/discourse/initializers/discourse-calendar.js

@@ -1,5 +1,6 @@
 import { isPresent } from "@ember/utils";
 import $ from "jquery";
+import { escape } from "pretty-text/sanitizer";
 import { Promise } from "rsvp";
 import { ajax } from "discourse/lib/ajax";
 import loadScript from "discourse/lib/load-script";
@@ -581,7 +582,7 @@ function initializeDiscourseCalendar(api) {
     if (detail.message.length > 100) {
       popupText += "…";
     }
-    event.extendedProps.htmlContent = popupText;
+    event.extendedProps.htmlContent = escape(popupText);
     event.title = event.title.replace(/<img[^>]*>/g, "");
     calendar.addEvent(event);
   }

assets/javascripts/discourse/lib/full-calendar-default-options.js

@@ -1,3 +1,4 @@
+import { escape } from "pretty-text/sanitizer";
 import {
   getCalendarButtonsText,
   getCurrentBcp47Locale,
@@ -13,7 +14,8 @@ export default function fullCalendarDefaultOptions() {
     buttonText: getCalendarButtonsText(),
     eventMouseEnter: function ({ event, jsEvent }) {
       destroyPopover();
-      const htmlContent = event.title;
+
+      const htmlContent = escape(event.title);
       buildPopover(jsEvent, htmlContent);
     },
     eventMouseLeave: function () {

plugin.rb

@@ -3,7 +3,7 @@
 # name: discourse-calendar
 # about: Adds the ability to create a dynamic calendar with events in a topic.
 # meta_topic_id: 97376
-# version: 0.4
+# version: 0.5
 # author: Daniel Waterworth, Joffrey Jaffeux
 # url: https://github.com/discourse/discourse-calendar
 

test/javascripts/acceptance/category-events-calendar-test.js

@@ -74,17 +74,51 @@ acceptance("Discourse Calendar - Category Events Calendar", function (needs) {
             },
             name: "Awesome Event 2",
           },
+          {
+            id: 67502,
+            starts_at: moment()
+              .tz("Asia/Calcutta")
+              .add(2, "days")
+              .format("YYYY-MM-DDT15:14:00.000Z"),
+            ends_at: moment()
+              .tz("Asia/Calcutta")
+              .add(2, "days")
+              .format("YYYY-MM-DDT16:14:00.000Z"),
+            timezone: "Asia/Calcutta",
+            post: {
+              id: 67502,
+              post_number: 1,
+              url: "/t/this-is-an-event/18451/1",
+              topic: {
+                id: 18451,
+                title: "This is an event",
+                category_slug: "awesome-category",
+              },
+            },
+            name: "Awesome Event 3<script>alert('my awesome event');</script>",
+          },
         ],
       });
     });
   });
 
+  test("event name is escaped correctly", async (assert) => {
+    await visit("/c/bug/1");
+
+    assert
+      .dom(".fc-event[href='/t/-/18451/1'] .fc-title")
+      .hasText(
+        "Awesome Event 3<script>alert('my awesome event');</script>",
+        "Elements should be escaped and appear as text rather than be the actual element."
+      );
+  });
+
   test("events display the color configured in the map_events_to_color site setting", async (assert) => {
     await visit("/c/bug/1");
 
     assert
       .dom(".fc-event")
-      .exists({ count: 2 }, "One event is displayed on the calendar");
+      .exists({ count: 3 }, "One event is displayed on the calendar");
 
     assert.dom(".fc-event[href='/t/-/18449/1']").hasStyle({
       "background-color": "rgb(231, 76, 60)",