Security Audit: Unconstrained string parameters across all official servers

Summary

I ran automated security audits on 7 official MCP servers using mcp-security-audit. All servers scored Grade A or B (85-100/100), which is great. But there's one consistent finding across every server except mcp-server-fetch:

No string parameters use maxLength, pattern, or enum constraints.

Findings

Why this matters

1. DoS vector — Unconstrained strings accept arbitrarily long input. A 10MB commit message or 50K-char file path must be processed by the server.
2. No boundary validation — If an LLM is compromised via prompt injection, the tool schema provides no defense against malformed input.
3. Network transports — With MCP supporting Streamable HTTP, servers may be network-exposed where these constraints become critical.

Suggested fix

One line per parameter:

{
  "name": "path",
  "type": "string",
  "maxLength": 4096
}

For known-format params:

{
  "name": "timezone",
  "type": "string",
  "pattern": "^[A-Za-z_/]+$",
  "maxLength": 50
}

Full reports

Individual JSON/text reports for each server: LuciferForge/mcp-audit-reports

The audit tool: pip install mcp-security-audit

Happy to discuss findings or help with fixes.

Start by reviewing the linked mcp-audit-reports for the seven official servers and reproducing the findings with mcp-security-audit. Inventory the unconstrained string parameters across SQLite, Time, GitHub, Memory, Git, and Filesystem, then verify that appropriate schema constraints address the reported findings without changing Fetch's already passing result.