How to meet it
OWASP AISVS v1.01
Model Context Protocol (MCP) Security · Secure Transport
Sender-constrained MCP tokens
Verify that access tokens between the MCP client and server are sender-constrained using mTLS or DPoP.
OWASP AISVS v1.01, requirement 10.3.5
In plain English
Bind access tokens to the client that holds them using mTLS or DPoP, so a stolen token cannot be used from elsewhere.
What good looks like
- Tokens are sender-constrained.
- The server checks the binding on each request.
- Unbound tokens are rejected.
How teams usually do it
- DPoP proofs or mTLS-bound tokens from your authorisation server.
Evidence an auditor would accept
- Configuration and a test using a token from a different client.
Common mistakes
- Issuing bound tokens but not checking the binding.
Not sure which requirements apply to your system? Take the assessment.
Requirement text from the OWASP AI Security Verification Standard, licensed under CC BY-SA 4.0. This guidance is shared under the same licence.