OAuth 2.1 and Modern Authentication: A Security Deep Dive
oauthsecurityauthentication
OAuth 2.1 and Modern Authentication: A Security Deep Dive
April 15, 2026
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Paal Gyula
gyula@pilab.hu
Understanding OAuth 2.1, OpenID Connect, and modern authentication patterns for securing APIs and applications.
Introduction
OAuth 2.1 consolidates the best practices from years of OAuth 2.0 deployments into a single, clearer specification.
Key Topics to Cover
- OAuth 2.1 vs OAuth 2.0: What changed?
- Authorization Code Flow with PKCE
- Client Credentials for service-to-service auth
- Token security and rotation
- Common vulnerabilities and how to prevent them
- OpenID Connect for identity layer
- Implementing SSO with 3SO