go-sdk/examples
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Filename Latest commit message Latest commit date
Max Gerber 2d47cc9664
auth: issuer mix-up mitigation (#859)
This PR functions as a Reference implementation of
[SEP-2468](https://github.com/modelcontextprotocol/modelcontextprotocol/pull/2468)
/ [RFC9207](https://datatracker.ietf.org/doc/rfc9207/).

This PR hardens the MCP OAuth Client functionality against Mix-Up
attacks:
>   Mix-up attacks aim to steal an authorization code or access token by
>   tricking the client into sending the authorization code or access
> token to the attacker instead of the honest authorization or resource
>   server

This PR hardens the client by adding support for a new `iss` parameter
in authorization responses:
- Authorization Servers broadcast support for the `iss` parameter via
the `authorization_response_iss_parameter_supported` metadata parameter
- If the parameter is supported, clients expect to receive the `iss`
parameter in the authorization response
- Clients compare the `iss` parameter in the authorization response to
the `Issuer` parameter in the authorization metadata. The two must match
exactly for the response to be processed.

Fixes #941
2026-05-27 11:39:08 +02:00
..
auth auth: issuer mix-up mitigation (#859) 2026-05-27 11:39:08 +02:00
client all: modernize code (#868) 2026-03-31 10:58:02 +02:00
http Update README.md (#896) 2026-04-24 11:47:17 +02:00
server auth: issuer mix-up mitigation (#859) 2026-05-27 11:39:08 +02:00