Interview question · Mobile Application Security

How can deep links and custom URL schemes be hijacked or abused, and how do verified app links fix it?

Any app can claim myapp://. That single fact breaks OAuth redirects, password-reset links and payment flows that trust a custom scheme. The fix is a link the operating system verifies against your domain.

mediumNewPreparation tags: Apple, Google, MetaUpdated Nov 2026

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A mobile app uses a custom URL scheme to receive OAuth login callbacks and password reset links.

Why are custom URL schemes risky?
What protects OAuth callbacks?
What about reset and magic links?
Why are deep links also an input channel?
How do you verify link configuration?
How would you fix the login and reset flows?

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Next in this trackWhat are the security risks of WebViews in mobile apps, especially with JavaScript bridges, and how do you design one safely?Next in this trackBeyond storage, where does sensitive data leak from a mobile app, and how do you find and close each leak?Next in this trackThreat-model a mobile banking app. Which controls belong on the device, and which must stay on the server?

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