# Mobile link handler trusts routing as authorization

An externally supplied custom or universal/app link reaches a protected client operation without validating the route input and current security context.

**Candidate CWE:** [CWE-939](https://cwe.mitre.org/data/definitions/939.html) · [CWE-863](https://cwe.mitre.org/data/definitions/863.html)

## Test hypothesis

Open a known benign link, then vary one resource or callback parameter across logged-out/account-switched states. Keep callbacks and test objects owned.

## Evidence required

Exact URL, OS routing, eligible build, current account, handler path and resulting protected capability; document callback verification when relevant.

## Rule out false positives

A verified domain association does not prove parameter safety. A custom scheme existing or a public route opening is not a vulnerability by itself.

## Playbook and command references

- [Android components, intents and deep links](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/modules/android-components.html) — Trace ordinary-app inputs through exported components, URI grants and links to one protected operation.
- [iOS signing capabilities, links and protected data](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/modules/ios-boundaries.html) — Connect entitlements and application groups to actual callers, URL transitions and protected key use.
- [Authentication, recovery, federation, and session lifecycle](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/modules/identity-session.html) — Test registration, recovery, identity changes, invitations, SSO enforcement, and deprovisioning as one account state machine.
- [Object, function, and property authorization](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/modules/authz-matrix.html) — Turn identities, tenants, objects, roles, and lifecycle transitions into a reproducible permission matrix.

[Find the associated command snippets](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/commands.html?q=Android%20components%2C%20intents%20and%20deep%20links)

## Referenced by these target playbooks

[Mobile](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/mobile.html)

## Report checklist

- [ ] Capture the affected version, configuration, identities, and object ownership.
- [ ] Preserve a valid baseline and a negative control.
- [ ] Reproduce the forbidden data access, action, or state change on controlled fixtures.
- [ ] Explain the intended security rule and why the observed behavior violates it.
- [ ] State prerequisites, uncertainty, cleanup, and the smallest demonstrated impact.

## Conditional ATT&CK mapping

No direct ATT&CK mapping selected. Record the weakness and demonstrated impact without forcing an adversary-behavior classification. See the [mapping guide](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/attack.html).

## Primary references

- [Android deep-link risks](https://developer.android.com/privacy-and-security/risks/unsafe-use-of-deeplinks)
- [Apple universal links](https://developer.apple.com/library/archive/documentation/General/Conceptual/AppSearch/UniversalLinks.html)

[Back to the complete vulnerability catalog](https://bug-bounty-field-manual.kmahshooq.chatgpt.site/vulnerabilities.html)