MCP Server Security Standard (MSSS)

About MSSS

The Model Context Protocol enables AI models to interact with external systems through tools, resources, and prompts. As adoption accelerates, critical vulnerabilities have emerged: command injection, path traversal, SSRF attacks, and supply chain compromises.

MSSS provides:

• 24 security controls across 8 domains
• 4 compliance levels (L1-Essential, L2-Development, L3-Production, L4-Maximum Assurance)
• Risk-based level selection framework inspired by NIST CSF, OWASP ASVS, and CIS Controls
• 6 deployment profiles (Local Dev, Team Server, Internet-Facing, etc.)
• Evidence-based verification with clear acceptance criteria
• Machine-readable reporting through JSON schemas

Compliant Platforms

The following platforms have adopted the MCP Server Security Standard:

-	Platform	Description	Status
	MCP-Hub	MCP server directory and marketplace — discover, publish, and manage MCP-compliant servers	✅ Compliant

Are you implementing MSSS? Open an issue or submit a PR to be listed here.

Current Status - v0.1.0

Released: January 15, 2026 (Community Review Draft)

What's Included

• Core standard framework (msss.md)
• 6 deployment profiles defined
• Comprehensive threat model
• 23 fully documented security controls
• JSON reporting schemas
• i18n framework for translations

Areas for Community Contribution

• Implementation examples for common frameworks
• Automated verification tools
• Reference assessment reports
• Translations to other languages
• Real-world testing and feedback

Quick Start

For Implementers

1. Review deployment profiles to find your scenario
2. Implement controls from control catalog
3. Use reporting schemas for assessment
4. Share your experience via issues or discussions

For Contributors

# Fork and clone
git clone https://github.com/YOUR-USERNAME/mcp-server-security-standard
cd mcp-server-security-standard

# Start a translation
mkdir -p v0.1/i18n/es/standard

For Security Researchers

• Report vulnerabilities: security@mcp-security-standard.org
• Share attack patterns: Open an issue with threat-research label
• Propose new controls: See contributing guide

Compliance Levels

MSSS defines four compliance levels using a risk-based selection model (not maturity progression). Organizations select their target level based on deployment context, data sensitivity, and potential impact.

Level Selection Framework

Level	Target Audience	Controls	Validation	Timeline
L1: Essential	Personal/Hobby	6 (25%)	Self-assessment	1-2 hours
L2: Development	Internal/Team	12 (50%)	Self + scanning	4-8 hours
L3: Production	Enterprise/Customers	18 (75%)	Internal audit	1-2 weeks
L4: Maximum Assurance	Critical/Regulated	24 (100%)	Third-party pentest	4-8 weeks

Quick Decision Guide

Choose your level based on 4 key questions:

1. Who uses it? Individual → L1 | Team → L2 | Organization/Customers → L3 | Public/Regulated → L4
2. What data? Public → L1 | Internal → L2 | Business/PII → L3 | Regulated (PHI/PCI) → L4
3. Impact if compromised? Inconvenience → L1 | Dev delays → L2 | Disruption → L3 | Severe harm → L4
4. Threat model? Opportunistic → L1 | Semi-targeted → L2 | Targeted → L3 | APT → L4

Level Highlights

Level 1 (Essential)

• Essential protection for personal tools and hobby projects
• Prevents: Command injection, path traversal, SSRF, credential leaks
• Key controls: No shell execution, path allowlisting, URL validation, schema validation, secret redaction

Level 2 (Development)

• Security for development teams and internal tools
• Adds: TLS enforcement, input bounds, timeouts, command allowlisting, trusted sources
• Required for: Team projects, internal apps, pre-production environments

Level 3 (Production)

• Comprehensive security for enterprise and customer-facing applications
• Adds: OAuth authentication, RBAC, audit logging, container hardening
• Required for: SaaS products, customer data, business-confidential information

Level 4 (Maximum Assurance)

• Maximum hardening for critical infrastructure and regulated environments
• Adds: Filesystem sandboxing, egress filtering, seccomp/AppArmor, runtime monitoring
• Required for: HIPAA (healthcare), PCI DSS (payments), FedRAMP (government)

📖 Full documentation: See Compliance Levels and Control-Level Mapping

Regulatory Mappings

• HIPAA (Healthcare): Level 4 minimum for PHI access
• PCI DSS (Payments): Level 4 minimum for cardholder data
• SOC 2 (SaaS): Level 3 minimum
• ISO 27001: Level 3 minimum for certification
• FedRAMP: Low→L3, Moderate/High→L4

Control Catalog

Filesystem (FS)

Control	Level	Description
MCP-FS-01	L1	Path allowlisting to prevent unauthorized file access
MCP-FS-02	L1	Symlink resolution to prevent path traversal via symbolic links
MCP-FS-03	L4	Filesystem sandboxing for complete isolation

Execution (EXEC)

Control	Level	Description
MCP-EXEC-01	L1	Avoid shell execution to prevent command injection
MCP-EXEC-02	L2	Command allowlisting for permitted executables
MCP-EXEC-03	L2	Argument separation to prevent injection attacks

Network (NET)

Control	Level	Description
MCP-NET-01	L1	URL validation to prevent SSRF attacks
MCP-NET-02	L4	Egress traffic filtering with destination allowlists
MCP-NET-03	L2	TLS 1.2+ enforcement for all remote connections

Authorization (AUTHZ)

Control	Level	Description
MCP-AUTHZ-01	L3	OAuth 2.1 delegation for secure authentication
MCP-AUTHZ-02	L3	Per-tool scope definition with granular permissions
MCP-AUTHZ-03	L3	Least privilege tool design principles
MCP-AUTHZ-04	L3	Resource-based access control (RBAC)

Input Validation (INPUT)

Control	Level	Description
MCP-INPUT-01	L1	JSON Schema validation for all tool arguments
MCP-INPUT-02	L2	Input bounds checking to prevent DoS attacks
MCP-INPUT-03	L2	Timeout enforcement for resource exhaustion prevention

Logging (LOG)

Control	Level	Description
MCP-LOG-01	L3	Comprehensive audit logging for all tool invocations
MCP-LOG-02	L1	Automatic secret redaction in logs

Supply Chain (SUPPLY)

Control	Level	Description
MCP-SUPPLY-01	L4	Package integrity verification with checksums
MCP-SUPPLY-02	L2	Trusted package sources and registry verification

Deployment (DEPLOY)

Control	Level	Description
MCP-DEPLOY-01	L3	Container hardening with security best practices
MCP-DEPLOY-02	L4	System call filtering via seccomp/AppArmor
MCP-DEPLOY-03	L4	Resource limits and rate limiting for DoS prevention

Total: 24 controls across 8 security domains

• Level 1: 6 controls (25%) - Essential baseline
• Level 2: 12 controls (50%) - Development protection
• Level 3: 18 controls (75%) - Production security
• Level 4: 24 controls (100%) - Maximum assurance

How to Contribute

We follow a simple process:

1. Pick an area - Check issues labeled help-wanted or good-first-issue
2. Discuss - Open an issue or join discussions before major work
3. Submit - Create a PR with clear description
4. Iterate - Address feedback from reviewers

Priority Contributions

HIGH PRIORITY

• Add real-world implementation examples
• Create reference implementations for common frameworks
• Test controls against production deployments

MEDIUM PRIORITY

• Add profile-specific guidance
• Start Spanish, Portuguese, or other translations
• Develop automated verification tools

ALWAYS WELCOME

• Fix typos and improve clarity
• Add references to new CVEs or research
• Share implementation experiences

Community

Get Involved

• Discussions: GitHub Discussions - Ask questions, share ideas
• Issues: GitHub Issues - Report bugs, request features

Project Lead

• Daniel García (cr0hn) - @cr0hn
• Dr. Alfonso Múñoz (Mindcrypt) Mindcrypt

Looking for Co-Maintainers! If you're passionate about MCP security and want to help shape this standard, please reach out.

Recognition

All contributors will be recognized in:

• CHANGELOG.md for significant contributions
• Control documents you author or substantially improve

Roadmap

v0.1 (Current - Community Review)

• Gather feedback on 23 controls
• Validate against real-world deployments
• Collect implementation experiences

v0.2 (Q2 2026)

• Incorporate community feedback
• Add controls for emerging threats
• Publish reference implementations
• Launch translation program

v1.0 (Q4 2026)

• Stable specification
• Automated verification tools
• Certification program framework
• Training materials

Related Standards

MSSS complements:

• OWASP MCP Top 10 - Risk categories
• OWASP ASVS - Verification standard
• CWE - Weakness enumeration
• NIST Cybersecurity Framework - Risk management

License

MSSS uses a multi-license approach:

Component	License	Purpose
Standard Text	CC BY-SA 4.0	Free sharing with attribution
JSON Schemas	Apache 2.0	Commercial tool integration
Code Examples	MIT	Maximum flexibility

See the full license text in the LICENSE file.

Support the Project

• Star this repository - Help others discover MSSS
• Share with your network - Spread awareness
• Contribute - Your expertise makes MSSS better

Acknowledgments

MSSS builds upon:

• Security researchers who disclosed MCP vulnerabilities
• OWASP MCP Top 10 community
• Early adopters providing feedback
• Academic researchers (MCPLIB, Hou et al.)

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The MCP Server Security Standard is an open community project. We provide this standard as-is without warranties. Use at your own discretion.