oauth21-security

To enforce OAuth 2.1 security, apply strict TLS across all endpoints, mandate PKCE for public clients, use exact redirect_uri matching with 303 redirects, and implement sender-constrained tokens like DPoP or Mutual TLS to prevent token replay.

OAuth 2.1 requires PKCE to prevent authorization code interception, making it mandatory for public clients and strongly recommended for confidential ones. The Implicit and Resource Owner Password Credentials grants are removed, encouraging Authorization Code with PKCE.

OAuth 2.1 TLS configuration requires enforcing TLS on all endpoints with specific loopback exceptions for native apps. It provides strict TLS version guidance to ensure secure token flows and protect against downgraded connection vulnerabilities.

Prevent token replay in OAuth 2.1 by implementing sender-constrained tokens. This involves applying token binding options including DPoP (Demonstrating Proof-of-Possession) and Mutual TLS to bind tokens to a specific client, preventing unauthorized token usage.

Yes, OAuth 2.1 supports loopback redirects for native apps with TLS exceptions. Secure redirect handling requires exact redirect_uri matching and recommends using specific status codes like 303 See Other to ensure proper and safe navigation during the authorization flow.

OAuth 2.1 works with both confidential and public clients. PKCE is mandatory for public clients and strongly recommended for confidential clients, ensuring secure authorization code flows across web, native, and mobile scenarios that demand robust server and client protections.