confused deputy fix in example + supporting sdk changes #648
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pcarleton
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May 7, 2025
| @@ -218,6 +219,26 @@ async def error_response( | |||
| ) | |||
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| try: | |||
| # Check if client has already consented | |||
| has_consent = await self.provider.has_client_consent(client) | |||
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todo: check client_consent_required before doing this
src/mcp/server/auth/provider.py
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| @@ -174,6 +174,27 @@ async def authorize( | |||
| """ | |||
| ... | |||
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| async def has_client_consent(self, client: OAuthClientInformationFull) -> bool: | |||
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todo: if client_consent_required, these need to be required, but otherwise they should be optional. open to suggestions here. i think a default implementation of return True means we'd solve for being optional, but not for required.
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Motivation and Context
See the confused deputy consideration here:
https://github.com/modelcontextprotocol/modelcontextprotocol/blob/c255349bd98d9dc73f3579c828d195bd09c0bee8/docs/specification/draft/basic/security_best_practices.mdx#21-confused-deputy-problem
In the example, we front the Github API, so we need to put a consent screen for each new client registration, otherwise the Github consent screen will be skipped for new clients, creating a path for token leakage.
Still TODO:
Here's what the consent screen looks like:
How Has This Been Tested?
Tested using inspector to run through auth flow
Breaking Changes
Types of changes
Checklist
Additional context