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Feat: Add RFC 7523 (JWT Bearer Grant) support#875

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ZachGerman wants to merge 2 commits intomodelcontextprotocol:mainfrom
ZachGerman:RFC-7523-support
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Feat: Add RFC 7523 (JWT Bearer Grant) support#875
ZachGerman wants to merge 2 commits intomodelcontextprotocol:mainfrom
ZachGerman:RFC-7523-support

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@ZachGerman
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@ZachGerman ZachGerman commented Aug 14, 2025 •
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Adds support for JWT Credentials passed to the OAuthClientProvider.
Also added a JWT OAuth client in the examples directory.

Motivation and Context

This provides support for machine-to-machine auth.

How Has This Been Tested?

Tested E2E via Auth0.

Breaking Changes

  • Now requiring codeVerifier for token exchange, but I'm pretty sure it's desirable behavior since PKCE is required per MCP spec.

Types of changes

  • Bug fix (non-breaking change which fixes an issue)
  • New feature (non-breaking change which adds functionality)
  • Breaking change (fix or feature that would cause existing functionality to change)
  • Documentation update

Checklist

  • I have read the MCP Documentation
  • My code follows the repository's style guidelines
  • New and existing tests pass locally
  • I have added appropriate error handling
  • I have added or updated documentation as needed

Additional context

Draft until tested end-to-end. Tested E2E via Auth0.
Bloated jwt-utils, as I was oiriginally going to add it to the built-in AS, but did a 180. Leaving it as-is in case someone wants to add built-in AS support for JWT.

@ZachGerman ZachGerman force-pushed the RFC-7523-support branch 4 times, most recently from 7092743 to 1094286 Compare August 19, 2025 04:58
@ZachGerman ZachGerman marked this pull request as ready for review August 19, 2025 05:04
@ZachGerman ZachGerman requested review from a team, felixweinberger and pcarleton August 19, 2025 05:04
@ZachGerman
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ZachGerman commented Sep 26, 2025

@pcarleton @felixweinberger Any review possible for this some time soon?

@yannj-fr
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yannj-fr commented Oct 28, 2025 •
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Considering the recent change (the spec is now part of ext-auth). We took the approach to have this in mcp.client.auth.extensions.client_credentials in the python SDK to highligh the "extension". I think this might be wise to find a similar way for typescript sdk

@felixweinberger felixweinberger mentioned this pull request Oct 30, 2025
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@felixweinberger felixweinberger linked an issue Nov 11, 2025 that may be closed by this pull request
Implement SEP-1046: Support OAuth client credentials flow in authorization #921
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@felixweinberger felixweinberger added auth Issues and PRs related to Authentication / OAuth breaking change Will break existing deployments when updated without changes v2 Ideas, requests and plans for v2 of the SDK which will incorporate major changes and fixes labels Dec 19, 2025
@felixweinberger
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felixweinberger commented Dec 19, 2025

Hey @ZachGerman - sorry this sat without review! We're triaging old PRs.

Question for @pcarleton: does this need an ext-auth spec first like client credentials did with SEP-1046?

@KKonstantinov
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KKonstantinov commented Dec 20, 2025

@felixweinberger JWT assertion on the client_credentials grant was added in #1157

Adding JWT bearer grant is quite easily achieved following the same pattern (if started from main), but it might be too much effort to resolve conflicts on this PR and achieve it.

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@pcarleton pcarleton Awaiting requested review from pcarleton

@felixweinberger felixweinberger Awaiting requested review from felixweinberger

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auth Issues and PRs related to Authentication / OAuth breaking change Will break existing deployments when updated without changes v2 Ideas, requests and plans for v2 of the SDK which will incorporate major changes and fixes

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Implement SEP-1046: Support OAuth client credentials flow in authorization

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@ZachGerman @yannj-fr @felixweinberger @KKonstantinov