#
Introducing Ayeixa MCP Guardian: Capability Fencing & Parameter Sanitization for MCP
Model Context Protocol (MCP) empowers language models to interact directly with databases, filesystems, and CLI utilities. However, exposing tool APIs creates security vulnerabilities: unauthorized directory traversal (../../etc/passwd
), destructive shell commands (rm -rf
), and untracked actions.
Ayeixa MCP Guardian (@ayeixa/mcp-guardian
) is a runtime capability fence and parameter sanitization middleware for Model Context Protocol servers and client tool invocations.
#
- Core Architecture
MCP Guardian operates as an interceptor middleware:
ToolPermissionFence: Enforces granular Role-Based Access Control (RBAC) and explicit tool allowlists/denylists. #
InvocationSanitizer: Sanitizes parameter arguments, blocking directory traversal patterns (../
) and dangerous system commands (sudo
, rm -rf
, chmod 777
). #
RuntimeAuditLogger: Records every invocation payload, argument set, and permission verdict into a tamper-evident SHA-256 cryptographic hash chain. #
GuardianSandbox: Permission-gated execution wrapper evaluating authorization rules and logging audit records before dispatching to tool executors.
#
- Implemented Capabilities & Test Verification
Verified with hermetic unit tests:
Permission Fencing: RBAC and denied command enforcement (tests/permission.test.ts
). #
Audit Ledger: Cryptographic hash chain validation (tests/audit.test.ts
). #
Execution Wrapper: Permission-gated dispatch and error containment (tests/sandbox.test.ts
).
Verification: 6/6 hermetic unit tests passing (0 failures).
#
- Local Quick Start
Usage Example
#
- Limitations & Contributing
- Pre-release
v0.1.0-alpha
. Provides application-level permission gating and parameter sanitization.
- Public npm publication is pending.
- We encourage security developers and researchers to contribute. See open
good first issue
tags on GitHub.
License: Apache-2.0