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, orcode_challenge - Mobile or SPA clients rely on OAuth or OIDC flows
For token cryptography and JWT header abuse, also load:
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
- Map the full flow: authorize, callback, token exchange, logout.
- Replay callback flows with altered
state,nonce, andredirect_uri. - Compare SPA, mobile, and web clients for weaker validation.
- 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
- XML federation or enterprise SSO: saml sso assertion attacks
- CSRF-heavy login or binding bugs: csrf cross site request forgery