diff --git a/package-lock.json b/package-lock.json
index 2b42a6992..7623fa790 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -3773,7 +3773,7 @@
       "from": "git+https://github.com/moodlemobile/cordova-plugin-wkuserscript.git"
     },
     "cordova-plugin-wkwebview-cookies": {
-      "version": "git+https://github.com/moodlemobile/cordova-plugin-wkwebview-cookies.git#8e319b9cc5887611bd8972152e4377757986d570",
+      "version": "git+https://github.com/moodlemobile/cordova-plugin-wkwebview-cookies.git#8c3a289e29b33edecff15f470c1630baf4ec3e88",
       "from": "git+https://github.com/moodlemobile/cordova-plugin-wkwebview-cookies.git"
     },
     "cordova-plugin-zip": {
diff --git a/src/assets/js/iframe-recaptcha.js b/src/assets/js/iframe-recaptcha.js
new file mode 100644
index 000000000..f1ff5e843
--- /dev/null
+++ b/src/assets/js/iframe-recaptcha.js
@@ -0,0 +1,42 @@
+// (C) Copyright 2015 Moodle Pty Ltd.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+(function () {
+    var url = location.href;
+
+    if (!url.match(/^https?:\/\//i) || !url.match(/\/webservice\/recaptcha\.php/i)) {
+        // Not the recaptcha script, stop.
+        return;
+    }
+
+    // Define recaptcha callbacks.
+    window.recaptchacallback = function(value) {
+        window.parent.postMessage({
+            environment: 'moodleapp',
+            context: 'recaptcha',
+            action: 'callback',
+            frameUrl: location.href,
+            value: value,
+        }, '*');
+    };
+
+    window.recaptchaexpiredcallback = function() {
+        window.parent.postMessage({
+            environment: 'moodleapp',
+            context: 'recaptcha',
+            action: 'expired',
+            frameUrl: location.href,
+        }, '*');
+    };
+})();
\ No newline at end of file
diff --git a/src/components/recaptcha/recaptchamodal.ts b/src/components/recaptcha/recaptchamodal.ts
index 1280e569f..2cff04c18 100644
--- a/src/components/recaptcha/recaptchamodal.ts
+++ b/src/components/recaptcha/recaptchamodal.ts
@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-import { Component } from '@angular/core';
+import { Component, OnDestroy } from '@angular/core';
 import { ViewController, NavParams } from 'ionic-angular';
 
 /**
@@ -22,13 +22,19 @@ import { ViewController, NavParams } from 'ionic-angular';
     selector: 'core-recaptcha-modal',
     templateUrl: 'core-recaptchamodal.html'
 })
-export class CoreRecaptchaModalComponent {
+export class CoreRecaptchaModalComponent implements OnDestroy {
     expired = false;
     value = '';
     src: string;
 
+    protected messageListenerFunction: (event: MessageEvent) => Promise<void>;
+
     constructor(protected viewCtrl: ViewController, params: NavParams) {
         this.src = params.get('src');
+
+        // Listen for messages from the iframe.
+        this.messageListenerFunction = this.onIframeMessage.bind(this);
+        window.addEventListener('message', this.messageListenerFunction);
     }
 
     /**
@@ -51,18 +57,63 @@ export class CoreRecaptchaModalComponent {
         const contentWindow = iframe && iframe.contentWindow;
 
         if (contentWindow) {
-            // Set the callbacks we're interested in.
-            contentWindow['recaptchacallback'] = (value): void => {
-                this.expired = false;
-                this.value = value;
-                this.closeModal();
-            };
-
-            contentWindow['recaptchaexpiredcallback'] = (): void => {
-                // Verification expired. Check the checkbox again.
-                this.expired = true;
-                this.value = '';
-            };
+            try {
+                // Set the callbacks we're interested in.
+                contentWindow['recaptchacallback'] = this.onRecaptchaCallback.bind(this);
+                contentWindow['recaptchaexpiredcallback'] = this.onRecaptchaExpiredCallback.bind(this);
+            } catch (error) {
+                // Cannot access the window.
+            }
         }
     }
+
+    /**
+     * Treat an iframe message event.
+     *
+     * @param event Event.
+     * @return Promise resolved when done.
+     */
+    protected async onIframeMessage(event: MessageEvent): Promise<void> {
+        if (!event.data || event.data.environment != 'moodleapp' || event.data.context != 'recaptcha') {
+            return;
+        }
+
+        switch (event.data.action) {
+            case 'callback':
+                this.onRecaptchaCallback(event.data.value);
+                break;
+            case 'expired':
+                this.onRecaptchaExpiredCallback();
+                break;
+
+            default:
+                break;
+        }
+    }
+
+    /**
+     * Recapcha callback called.
+     *
+     * @param value Value received.
+     */
+    protected onRecaptchaCallback(value: any): void {
+        this.expired = false;
+        this.value = value;
+        this.closeModal();
+    }
+
+    /**
+     * Recapcha expired callback called.
+     */
+    protected onRecaptchaExpiredCallback(): void {
+        this.expired = true;
+        this.value = '';
+    }
+
+    /**
+     * Component destroyed.
+     */
+    ngOnDestroy(): void {
+        window.removeEventListener('message', this.messageListenerFunction);
+    }
 }
diff --git a/src/providers/utils/iframe.ts b/src/providers/utils/iframe.ts
index e477e7401..be188bbb1 100644
--- a/src/providers/utils/iframe.ts
+++ b/src/providers/utils/iframe.ts
@@ -27,7 +27,7 @@ import { CoreUtilsProvider } from './utils';
 import { CoreContentLinksHelperProvider } from '@core/contentlinks/providers/helper';
 import { makeSingleton } from '@singletons/core.singletons';
 import { CoreUrl } from '@singletons/url';
-import { WKUserScriptWindow } from 'cordova-plugin-wkuserscript';
+import { WKUserScriptWindow, WKUserScriptInjectionTime } from 'cordova-plugin-wkuserscript';
 
 /*
  * "Utils" service with helper functions for iframes, embed and similar.
@@ -50,8 +50,16 @@ export class CoreIframeUtilsProvider {
         if (platform.is('ios') && win.WKUserScript) {
             platform.ready().then(() => {
                 // Inject code to the iframes because we cannot access the online ones.
-                const path = textUtils.concatenatePaths(fileProvider.getWWWAbsolutePath(), 'assets/js/iframe-treat-links.js');
-                win.WKUserScript.addScript({id: 'CoreIframeUtilsScript', file: path});
+                const wwwPath = fileProvider.getWWWAbsolutePath();
+                const linksPath = textUtils.concatenatePaths(wwwPath, 'assets/js/iframe-treat-links.js');
+                const recaptchaPath = textUtils.concatenatePaths(wwwPath, 'assets/js/iframe-recaptcha.js');
+
+                win.WKUserScript.addScript({id: 'CoreIframeUtilsLinksScript', file: linksPath});
+                win.WKUserScript.addScript({
+                    id: 'CoreIframeUtilsRecaptchaScript',
+                    file: recaptchaPath,
+                    injectionTime: WKUserScriptInjectionTime.END,
+                });
 
                 // Handle post messages received by iframes.
                 window.addEventListener('message', this.handleIframeMessage.bind(this));