/oauth-oidc-misconfiguration

name: oauth-oidc-misconfiguration
description: >-
  OAuth and OIDC misconfiguration testing playbook. Use when reviewing redirect URI handling, state and nonce validation, PKCE, token audience, callback binding, and identity-provider trust flaws.

SKILL: OAuth and OIDC Misconfiguration — Redirects, PKCE, Scopes, and Token Binding

> **AI LOAD INSTRUCTION**: Use this skill when the target uses OAuth 2.0 or OpenID Connect and you need a focused misconfiguration checklist: redirect URI validation, state and nonce handling, PKCE enforcement, token audience, and account binding mistakes.

1. WHEN TO LOAD THIS SKILL

Load when:

• The app supports `Login with Google`, GitHub, Microsoft, Okta, or other IdPs
• You see `authorize`, `callback`, `redirect_uri`, `code`, `state`, `nonce`, or `code_challenge`
• Mobile or SPA clients rely on OAuth or OIDC flows

For token cryptography and JWT header abuse, also load:

• [jwt oauth token attacks](../jwt-oauth-token-attacks/SKILL.md)

2. HIGH-VALUE MISCONFIGURATION CHECKS

| Theme | What to Check | |---|---| | `state` handling | missing, static, predictable, or not bound to user session | | `redirect_uri` validation | prefix match, open redirect chaining, path confusion, localhost leftovers | | PKCE | missing for public clients, code verifier not enforced, downgraded flow | | OIDC `nonce` | missing or not validated on ID token return | | token audience and issuer | weak `aud` / `iss` checks, cross-client token reuse | | account binding | callback binds attacker identity to victim session | | scope handling | broader scopes granted than the user or client should receive |

3. QUICK TRIAGE

1. Map the full flow: authorize, callback, token exchange, logout. 2. Replay callback flows with altered `state`, `nonce`, and `redirect_uri`. 3. Compare SPA, mobile, and web clients for weaker validation. 4. Check whether one provider account can be rebound to another local account.

4. RELATED ROUTES

• CORS or cross-origin token exposure: [cors cross origin misconfiguration](../cors-cross-origin-misconfiguration/SKILL.md)
• XML federation or enterprise SSO: [saml sso assertion attacks](../saml-sso-assertion-attacks/SKILL.md)
• CSRF-heavy login or binding bugs: [csrf cross site request forgery](../csrf-cross-site-request-forgery/SKILL.md)