stoatchat versions before 0.7.8 fail to enforce account creation restrictions including invite-only mode, email verification, captcha, and shield verification. Attackers can create unlimited accounts with unverified email addresses, increasing denial-of-service risk and compromising service integrity.

## Summary `parseAndValidateClientRedirect` at `internal/service/auth/auth.go:448` validates OAuth client-redirect URIs by comparing only scheme and host against the admin-configured allowlist. Path, query, and fragment are ignored. The initiator at `/oauth/:provider/login` embeds the caller-supplied `redirect_uri` verbatim into the signed state JWT without any validation at login time. Alice sub