OAuth / OIDC / SSO abuse

When it applies

The app delegates auth via OAuth/OIDC (social login, enterprise SSO). Flaws here are frequently full account takeover.

Why it works

OAuth security depends on strict validation of redirect_uri, state, code binding, and how identities are linked. Implementations relax one of these — and the token/code that proves identity leaks to the attacker or an account gets linked to the wrong user.