Read the previous posts in this series:
- How to Use Model Context Protocol (MCP) the Right Way
- Model Context Protocol (MCP): What’s Changed, What Still Matters, What Comes Next
- MCP: Security, Maturity, and the Road to Enterprise Readiness
- Breaking the Wiring: Understanding and Mitigating MCP Attack Vectors
- MCP and Authentication: Building Secure Access in the Agentic Era
When people talk about the security of the Model Context Protocol, most of the conversation gravitates toward prompt injection or rogue tools. But beneath those headline risks sits something more fundamental: the supply chain.
MCP servers and their tools are not static, shrink-wrapped products; they are living components that evolve, update, and sometimes disappear. Agents are designed to discover and compose them dynamically, which means MCP introduces a supply chain not just of code, but of behavior. If we fail to secure that chain, we risk creating a fragile foundation where even the most well-intentioned protocol design is undone by drift, compromise, or silent substitution.
Essential MCP Supply Chain Concepts
There are several concepts which are fundamental to the MCP supply chain. Here’s a primer:
Version Pinning
In software ecosystems we learned long ago that depending on “latest” is a recipe for instability and compromise. Yet many early MCP hosts still accept whatever schema or behavior a server exposes at runtime, treating the server as if it cannot change. That is wishful thinking.
A server can change because its maintainer updated it, because its repository was hijacked, or because its metadata was quietly rewritten. Without pinning a known version of a tool, agents are effectively delegating trust to the network in real time. The risk is not just outages, but rug pulls where safe behavior is swapped for malicious payloads. To mitigate this, platforms need to adopt immutable versioning of tools, with updates treated as deliberate events requiring review, not as background noise.
Cryptographic Signing
A tool descriptor is only as trustworthy as its provenance. If anyone can publish a JSON schema that looks well-formed, nothing prevents an attacker from impersonating a legitimate server. Signing descriptors and implementations ensures that what the agent consumes was authored by who it claims to be, and that it has not been tampered with en route.
In other ecosystems this is non-negotiable; we sign containers, binaries, even commit histories. MCP should be no different. The specification should move toward requiring signed artifacts as first-class citizens, while platforms need to verify those signatures before allowing a server into their catalogs. Without this, man-in-the-middle attacks and clone servers masquerading as trusted ones are inevitable.
Transparency Logs
These logs add the collective memory that the ecosystem currently lacks.
One of the greatest risks in MCP supply chains is the silent update. A server can push a new schema or change behavior, and unless you were watching at that exact moment, history is rewritten. Transparency logs, similar to what we now use for TLS certificates, provide an append-only record of tool versions and updates. They make it possible to audit when a server changed, compare deltas, and hold maintainers accountable.
For enterprises, transparency logs also offer a forensic trail to reconstruct how a compromised tool entered production. Without transparency, trust collapses into a snapshot: you only know what you have right now, not what it was yesterday, or who changed it.
Dependency Review and Attestation
MCP tools are rarely isolated. A server that exposes a function may rely on external libraries, third-party APIs, or system calls. If those dependencies are opaque, the attack surface balloons without visibility.
Attestations — machine-readable proofs of how a tool was built, with what dependencies, and in what environment — are already standardizing in other domains via efforts like SLSA. Extending MCP to encourage or even require attestations would bring the same benefits: reproducibility, verifiability, and the ability to block tools that were built with untrusted inputs. The risk without this is cascading compromise: a tool that looks fine at the MCP layer but pulls in a vulnerable library or a malicious API behind the curtain.
Catalog Governance
This is where specification and platform meet. The spec can define how tools are described, signed, and versioned. Platforms need to enforce how they are curated, admitted, and retired.
This requires maintaining trusted catalogs where every tool is vetted, every update is reviewed, and every retirement is logged. It also means building runtime controls: the ability to quarantine a tool if its signature fails, to block an update that drifts from expected behavior, to apply quotas and rate limits that insulate it from abuse, and to roll back to a safe version if a regression is discovered. Without catalog governance, the most carefully designed spec features will be bypassed by weak operational discipline.
Defense Against Agent Misuse
Platform responsibilities extend beyond securing inbound supply-chain risk; they must also defend the tools themselves against misuse by agents.
The promise of MCP is that agents can dynamically discover and invoke tools, but that promise is a double-edged sword. Without guardrails, a rogue or compromised agent can overwhelm a tool, either by flooding it with requests or by consuming resources in unexpected ways.
Quotas and rate limiting are the most obvious defenses here: enforcing hard caps on how often a tool can be invoked per agent, per tenant, or per time window. Beyond volume controls, platforms need fine-grained access rules that ensure an agent can only use a tool in ways consistent with policy — limiting parameters, constraining scope, and preventing recursive or looping behavior. Observability matters as well: audit logs and anomaly detection are required to spot when an agent begins to misuse a tool, whether through error or intent.
Protecting the tool is as important as protecting the agent, because a denial-of-service attack launched through MCP is not a hypothetical risk; it is a guaranteed failure mode if left unchecked.
The risks of leaving these issues unresolved are easy to imagine and hard to overstate. Without version pinning, workflows will break silently and attackers can swap tools undetected. Without signing, impersonation becomes trivial. Without transparency, no one can prove what happened when. Without attestations, supply-chain attacks slip past undetected. Without quotas and rate limits, even trusted tools can be knocked offline by misbehaving agents. And without governance, enterprises will inherit the chaos of the open internet inside their most sensitive AI workflows.
Next Steps for MCP Evolution: Embedded Supply Chain Security
The takeaway is clear. The MCP specification must evolve to embed supply chain security as a first-class concern: signed descriptors, immutable versioning, and transparency mechanisms should not be optional extras, but core features. AI and integration platforms, in turn, must implement the controls to enforce them: curated catalogs, runtime enforcement, behavioral drift detection, quotas, rate limits, and rollback.
Together, these steps can transform MCP from a powerful but fragile connector into a resilient backbone for agentic AI. The wiring works. Now we need to secure the circuit.
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This blog was written with the assistance of AI.