What is OAuth 2.1 Authorization Framework?

Understanding OAuth 2.1#

OAuth 2.1 consolidates security best practices developed over a decade of OAuth 2.0 implementations. It formally removes dangerous legacy authorization grant types (Implicit flow and Resource Owner Password Grant) and enforces PKCE everywhere.

Everyday Analogy#

A valet parking key: a mechanical key permitting the attendant to drive and park your vehicle without unlocking the glove compartment or opening the trunk safe.

Security Hardening Changes#

• Mandatory Proof Key for Code Exchange (PKCE) across all clients
• Total deprecation of the insecure Implicit Grant flow
• Exact string matching mandated on redirect URIs to thwart redirection hijacking