How to meet it
OWASP AISVS v1.01
Model Context Protocol (MCP) Security · Schema, Message, and Input Validation
Proxies don't share authorisation between clients
Verify that MCP proxy servers using a shared upstream OAuth client identity do not allow a requesting MCP client to inherit authorization established for a different MCP client.
OWASP AISVS v1.01, requirement 10.4.9
In plain English
A proxy that uses one shared OAuth identity upstream must not let one client inherit the authorisation granted to another.
What good looks like
- The proxy tracks authorisation per client.
- Each client must authorise on its own.
- Tests try to use another client's grant.
How teams usually do it
- Per-client consent records in the proxy.
Evidence an auditor would accept
- Proxy design and tests.
Common mistakes
- Caching upstream tokens in the proxy and reusing them for any client.
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Requirement text from the OWASP AI Security Verification Standard, licensed under CC BY-SA 4.0. This guidance is shared under the same licence.