Official MCP Python SDK Flaw Can Let Malicious Servers Steal OAuth Credentials

A vulnerability in the official MCP Python SDK can be exploited by a malicious server to obtain OAuth credentials from an application using the SDK. The malicious server can trick the application into sending sensitive information, including the client secret, authorization code, and PKCE proof key, to a token endpoint controlled by the attacker. The SDK's maintainers have issued a security advisory regarding the flaw. The issue is resolved in versions 1.30.0 and later of the SDK.