“OAuth 2.0 requires a complex redirection trail between websites and Identity Providers (IdPs). In particular, the ‘redirect URI’ parameter included in the popular Authorization Grant Code flow governs the callback endpoint that users are routed to, together with their security tokens. The protocol specification, therefore, includes guidelines on protecting the integrity of the redirect URI. … We analyze the OAuth 2.0 specification in light of modern systems-centric attacks and reveal that the prescribed redirect URI validation guidance exposes IdPs to path confusion and parameter pollution attacks.”

Find the paper and authors list in the 39th Annual Computer Security Applications Conference proceedings.