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docs(oauth): clarify code-injection ATO is code-grant-specific and PKCE's role - #18
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…w PKCE affects it Attack technique 4 (leaking codes/tokens through a lax AS) didn't state which grant type it applies to, or how PKCE changes the outcome once a code has leaked -- both real gaps an interviewer would probe. Clarifies: the attack is code-grant-specific (implicit leaks the token itself, no replay step needed, so it's not exempt, just a more direct version); and that the replay succeeds unconditionally against a confidential client (secret lives server-side) but is blocked against a correctly PKCE-bound public client, since the attacker's browser won't hold the matching code_verifier. Ties this back to why RFC 9700 recommends PKCE for confidential clients too, not just public ones -- it's the independent fix for the replay, where redirect_uri re-validation at /token is the fix for the leak.
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Summary
14-oauth-oidc.md("Leaking codes/tokens through a lax AS, the classic ATO") didn't state which grant type it applies to, or what actually determines whether the replay succeeds once a code has leaked.code_verifiergenerated by whichever browser called/authorize.redirect_urire-validation at/tokenis the fix for the leak — an AS needs both.Test plan
python -m pytest tests/— 11/11 passed.ref1RFC 9700,ref9RFC 7636) reused, no new sources needed.https://claude.ai/code/session_011f1KhQCYiUUPFKco7pguLC