They should remove static secrets from configuration files, environment variables, and code repositories, then replace them with runtime retrieval from a controlled vault. The goal is to shrink exposure windows and bind each credential to a specific agent, tool, and task boundary. Without that shift, MCP becomes a reusable access path rather than a governed identity layer.
Why This Matters for Security Teams
hardcoded credential in mcp server deployments turn a tool gateway into a durable secret distribution channel. That is a direct governance failure, not a simple configuration mistake, because MCP servers often sit between autonomous agents and sensitive systems. Once a secret is embedded in files, containers, or deployment manifests, it becomes hard to scope, hard to revoke, and easy to copy across environments.
The risk is especially acute because MCP adoption is still early and operational discipline is uneven. NHIMG research on The State of MCP Server Security 2025 found that 53% of MCP servers expose credentials through hard-coded values in configuration files. That aligns with broader secrets-sprawl findings in The State of Secrets Sprawl 2026, where exposed secrets continue to outlive the systems that leaked them. In parallel, the OWASP Non-Human Identity Top 10 treats secret exposure as an identity problem because the credential is what grants the workload power.
In practice, many security teams encounter MCP secret leakage only after a deployment, integration, or agent workflow has already made the credential reusable outside its intended boundary.
How It Works in Practice
The practical fix is to stop treating MCP server access as a static configuration concern and move to runtime credential retrieval. The server should authenticate itself as a workload, retrieve the secret only when a task begins, and discard it as soon as the task completes. That approach shortens exposure windows and makes compromise less reusable. Current guidance from the OWASP Top 10 for Agentic Applications 2026 and the NIST SP 800-63 Digital Identity Guidelines supports stronger proof of identity at runtime rather than implicit trust in stored secrets.
For MCP deployments, that usually means:
- Removing credentials from source code, build files, and environment variables wherever possible.
- Using a vault or secret broker that issues short-lived values only after the server proves its identity.
- Binding each secret to a specific MCP server, tool, environment, and task boundary.
- Automating revocation so expired credentials cannot be reused by another agent session.
- Logging secret retrieval events separately from tool invocation so security teams can detect abnormal reuse.
This model works best when the MCP server has a clear workload identity and the policy engine can decide access at request time, not at deployment time. The Ultimate Guide to NHIs — Static vs Dynamic Secrets is useful here because it frames the core issue correctly: a secret is not just a value to store, it is an authorization mechanism that should expire with the action it enables. That distinction matters when MCP is acting as a bridge for agents that may chain tools and cross system boundaries faster than human operators can review them. These controls tend to break down when teams reuse one long-lived secret across multiple MCP servers because the blast radius becomes impossible to contain.
Common Variations and Edge Cases
Tighter secret handling often increases operational overhead, requiring organisations to balance deployment simplicity against revocation speed and auditability. Some teams still use environment variables for non-production systems, but current guidance suggests that this should be treated as transitional at best, not a stable control.
There are a few edge cases worth calling out. First, if an MCP server must bootstrap before it can reach a vault, the bootstrap credential should be minimal, short-lived, and restricted to one retrieval path only. Second, if an agentic workflow spans multiple tools, each tool should receive its own credential or token scope instead of inheriting a shared server-wide secret. Third, if the deployment runs in CI/CD, treat the pipeline as part of the trust boundary because leaked secrets often originate there, not just in application code. NHIMG’s Guide to the Secret Sprawl Challenge is relevant because it shows how quickly secrets spread once they are embedded in ordinary delivery workflows.
Best practice is evolving, but one principle is stable: hardcoded credentials are incompatible with governed MCP operations. If the server can keep using the same secret after the task ends, the deployment has not removed standing privilege, it has merely hidden it.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
OWASP Non-Human Identity Top 10 and OWASP Agentic AI Top 10 address the attack and risk surface, while NIST AI RMF set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP Non-Human Identity Top 10 | NHI-03 | Covers hardcoded and overexposed non-human credentials in service deployments. |
| OWASP Agentic AI Top 10 | A2 | Agentic systems need runtime authorization, not static secrets. |
| NIST AI RMF | AI RMF governance applies to autonomous tool access and secret handling risk. |
Replace embedded MCP secrets with short-lived, vault-issued credentials and revoke them on task completion.
Related resources from NHI Mgmt Group
- How should security teams handle Dynamic Client Registration in remote MCP deployments?
- How should security teams decide whether JIT access is safe for non-human identities?
- How should organizations prioritize security in their MCP implementations?
- How should security teams handle leaked credentials reported outside bug bounty scope?
Deepen Your Knowledge
Reviewed and updated by the NHIMG editorial team on June 7, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org
