mpak Trust Framework
An open security standard for MCP server bundles
MTF defines four compliance levels across five security domains, enabling bundle authors, registries, and consumers to establish and verify security guarantees for AI tool extensions.
The Problem
MCP servers extend AI assistants with powerful capabilities: filesystem access, network requests, database queries, and code execution. This power creates significant security risk. A malicious or compromised MCP bundle can:
- Exfiltrate sensitive data from the user's environment
- Execute arbitrary code with user privileges
- Serve as a vector for supply chain attacks
- Poison AI behavior through tool description injection
Compliance Levels
Four levels of increasing security assurance. Start with L1 in minutes, progress to L4 for maximum trust.
Basic
Personal projects, experimentation
Minutes to achieve
- No embedded secrets
- No malicious patterns
- Valid manifest
- Tool declarations
- SBOM generation
Standard
Team tools, published packages
< 1 hour to achieve
- Vulnerability scanning (EPSS/KEV)
- Dependency pinning
- Static analysis
- Author identity
- Tool description safety
Verified
Production, enterprise use
Days to achieve
- Cryptographic signing
- Build attestation (SLSA)
- Input validation
- OpenSSF Scorecard
- Credential scope declaration
Attested
Critical infrastructure
Weeks to achieve
- Behavioral analysis
- Reproducible builds
- Commit linkage
- Full provenance chain
- Independent verification
MCP-Specific Security
MTF addresses attack surfaces unique to AI-assisted development that traditional package security tools miss.
Tool Description Poisoning
LLMs treat tool descriptions as trusted instructions. A malicious description can direct AI to exfiltrate data without user awareness.
CD-03 Slopsquatting
Attackers register package names commonly hallucinated by AI coding assistants, targeting AI-generated code rather than human typos.
CQ-06 Credential Blast Radius
MCP servers aggregate OAuth tokens for multiple services. Broad scopes create cascading breach potential across integrated services.
CD-04 Behavioral Mismatch
Dynamic analysis in isolated sandboxes verifies that declared permissions match actual runtime behavior.
CQ-07 Security Domains
Supply Chain
SBOM generation, vulnerability scanning with EPSS/KEV, dependency pinning, license compliance
Code Quality
Secret detection, malicious pattern scanning, static analysis, behavioral analysis
Artifact Integrity
Manifest validation, content hashes, cryptographic signatures, reproducible builds
Provenance
Source repository linkage, author identity, SLSA build attestation, OpenSSF Scorecard
Capability Declaration
Tool declarations, permission scopes, credential requirements, description safety
Resources
Specification v0.1
Full technical specification with 25 controls across all domains
JSON Schemas
Machine-readable schemas for manifests, reports, and VEX statements
Reference Scanner
Python implementation for automated MTF verification
MCPB Specification
The bundle format that MTF builds upon
mpak Registry
Discover and publish MTF-verified bundles