From 38ea8dcf9672effc9e9072478aaa6aad832c2418 Mon Sep 17 00:00:00 2001
From: PieterKas <90690777+PieterKas@users.noreply.github.com>
Date: Mon, 12 Oct 2026 12:10:10 +0100
Subject: [PATCH] Add authorization code binding recommendation (dpop_jkt)
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Adds a SHOULD for MCP clients to bind the authorization code to their DPoP key per RFC 9449 Section 10. RFC 9449 makes this OPTIONAL; this profile recommends it as defense in depth alongside MCP’s mandatory PKCE. Surfaced by the conformance work in modelcontextprotocol/conformance#523; kept separate from #33 so the two can be discussed and merged independently.
---
 specification/draft/dpop-extension.mdx | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/specification/draft/dpop-extension.mdx b/specification/draft/dpop-extension.mdx
index 20fafb1..20fac5b 100644
--- a/specification/draft/dpop-extension.mdx
+++ b/specification/draft/dpop-extension.mdx
@@ -59,6 +59,10 @@ DPoP: eyJ0eXAiOiJkcG9wK2p3dCIsImFsZyI6IkVTMjU2IiwiandrIjp7Imt0eSI6...
 
 ```
 
+### Authorization Code Binding
+
+MCP clients using the authorization code grant SHOULD bind the authorization code to their DPoP key, as described in [RFC 9449 Section 10](https://datatracker.ietf.org/doc/html/rfc9449#section-10).
+
 ### MCP Server Validation
 
 MCP servers MUST validate DPoP proofs according to [RFC 9449 Section 4.3](https://datatracker.ietf.org/doc/html/rfc9449#section-4.3). Implementations conforming to this specification MUST verify that the `iat` claim is within ±5 minutes of the server's current time.