MCP SEP-2468: RFC 9207 Iss Parameter for OAuth Mix-Up Defense
The Model Context Protocol (MCP) has updated its authorization flow to align with RFC 9207, enhancing security against OAuth mix-up attacks. This change mandates that authorization servers include an `iss` parameter in their responses, which clients must then validate against the originally recorded issuer. This structural defense prevents attackers from tricking clients into using authorization codes with the wrong identity provider, a vulnerability that previous session-based methods could not fully address. AI
IMPACT Enhances security for LLM agents interacting with external tools by preventing authentication mix-ups.