eslint-plugin-mcp-sdk-security

⭐ If this plugin caught a real bug for you, star the repo — it's the signal that keeps these rules maintained.

DescriptionCopy Anchor Link

Security rules for code built on @modelcontextprotocol/sdk.

Scope: this plugin lints the MCP SDK's API shapes — registerTool, transports, handler signatures. It does not inspect MCP wire traffic, which isn't visible from source. Every rule gates on the SDK actually being imported, so it stays silent in files that don't use MCP.

• Why — a linter nobody reads protects nothing. We would rather miss a finding than spend your attention on one that was never real.
• How — evidence, not names. A rule fires on what the code does, resolved through the AST and ESLint's own scope analysis.
• What — every finding carries its fix, in prose for a human and as structured JSON for an agent. Security rules add a CWE mapping and, where assigned, a CVSS score.

That trade costs recall, and we measure it: methodology · results · a false positive is a bug.

Getting StartedCopy Anchor Link

• To check out the guide, visit eslint.interlace.tools. 📚

oxlint / Vite+ — the same rules under the same mcp-sdk-security/<rule> IDs, without ESLint:

npm install oxlint-plugin-mcp-sdk-security --save-dev

// .oxlintrc.json
{ "jsPlugins": ["oxlint-plugin-mcp-sdk-security"] }

// vite.config.ts
import { defineConfig } from 'vite-plus';

export default defineConfig({ lint: { jsPlugins: ['oxlint-plugin-mcp-sdk-security'] } });

ESLint:

npm install eslint-plugin-mcp-sdk-security --save-dev

⚙️ Configuration PresetsCopy Anchor Link

Supported servers: @modelcontextprotocol/sdk (v1), the v2 split packages (@modelcontextprotocol/server, client, core, node, express, hono, fastify), and mcp-handler / @vercel/mcp-adapter. Every rule stays silent in a file that imports none of them.

What the rules cover:

• Tool handlers — a tool argument, request.params.arguments or a ResourceTemplate variable reaching a process (no-command-injection-in-tool), a file path (no-path-traversal-in-tool), a request host (no-ssrf-in-tool), SQL text (no-sql-injection-in-tool) or eval / vm (no-code-injection-in-tool); the environment or the caller's token in a result, or that token forwarded upstream (no-credential-leak-in-tool); the schema/handler contract (require-tool-input-schema, no-unvalidated-tool-args); one name registered twice (no-duplicate-tool-name).
• Model-facing text — a tool, prompt or resource description built from text a client, a remote service or a file controls (no-tool-description-injection).
• HTTP transports — DNS-rebinding protection, allowedHosts and authentication (require-http-transport-hardening), a stateless transport or server shared across requests (no-shared-stateless-transport, CVE-2026-25536), and predictable session IDs (no-predictable-session-id).
• Clients — a server's tool metadata written into an LLM prompt (no-untrusted-tool-metadata-in-prompt), and a stdio server command taken from a tool argument, a network response or project config (no-untrusted-stdio-command).

Each taint rule follows the value inside its handler — used directly, built into a string, or derived — and resolves sinks to the module that defines them. Tool handlers are this plugin's scope, so on the same line it may report alongside eslint-plugin-node-security (no-shell-injection, detect-non-literal-fs-filename, no-ssrf, detect-eval-with-expression) or eslint-plugin-secure-coding (no-sql-injection), which cover the same sinks outside MCP handlers. Each rule's doc states its overlap.

UsageCopy Anchor Link

// eslint.config.js
import mcpSdkSecurity from 'eslint-plugin-mcp-sdk-security';

export default [
  mcpSdkSecurity.configs.recommended,
];

Or wire the rules yourself:

import mcpSdkSecurity from 'eslint-plugin-mcp-sdk-security';

export default [
  {
    plugins: { 'mcp-sdk-security': mcpSdkSecurity },
    rules: {
      'mcp-sdk-security/require-tool-input-schema': 'error',
    },
  },
];

oxlintCopy Anchor Link

Every rule in this plugin runs on oxlint as well as ESLint:

{ "jsPlugins": ["eslint-plugin-mcp-sdk-security/oxlint"] }

📦 CompatibilityCopy Anchor Link

Package	Version
@modelcontextprotocol/sdk
ESLint
Node.js

See the ESLint Version Support Policy for the full matrix.

RulesCopy Anchor Link

Legend

⭐ Support & followCopy Anchor Link

If this plugin caught a real bug for you, star the repo — stars are the signal that keeps the Interlace ESLint ecosystem maintained — and follow the writeups on Dev.to for the benchmarks and security research behind these rules.

🔗 Related ESLint PluginsCopy Anchor Link

Part of the Interlace ESLint ecosystem — AI-native rules with LLM-optimized error messages:

Security

Plugin	Downloads	Description
eslint-plugin-anthropic-security		Anthropic SDK security.
eslint-plugin-browser-security		XSS, DOM security.
eslint-plugin-drizzle-security		Drizzle security.
eslint-plugin-express-security		Express middleware hardening.
eslint-plugin-gemini-security		Google Gemini SDK security.
eslint-plugin-jwt-security		Token security.
eslint-plugin-knex-security		Knex security.
eslint-plugin-lambda-security		AWS Lambda hardening.
eslint-plugin-mongodb-security		MongoDB injection.
eslint-plugin-mysql-security		MySQL security.
eslint-plugin-nestjs-security		NestJS framework hardening.
eslint-plugin-node-security		Server-side patterns.
eslint-plugin-openai-security		OpenAI SDK security.
eslint-plugin-postgresql-security		PostgreSQL security.
eslint-plugin-prisma-security		Prisma security.
eslint-plugin-secure-coding		Injection prevention.
eslint-plugin-sequelize-security		Sequelize ORM security.
eslint-plugin-sqlite-security		SQLite security.
eslint-plugin-supabase-security		Supabase security.
eslint-plugin-typeorm-security		TypeORM security.
eslint-plugin-vercel-ai-security		AI SDK security.

Code quality

Plugin	Downloads	Description
eslint-plugin-cli-floor		CLI floor for commander, yargs and burgee.
eslint-plugin-conventions		Team-specific habits and styles.
eslint-plugin-import-next		Fast cycle + import-graph analysis.
eslint-plugin-maintainability		Cognitive load and clean-code patterns.
eslint-plugin-modernization		ESNext migration + syntax evolution.
eslint-plugin-modularity		Structural integrity and DDD patterns.
eslint-plugin-operability		Production readiness and resource health.
eslint-plugin-react-a11y		React accessibility / WCAG.
eslint-plugin-react-features		React best practices and optimization.
eslint-plugin-reliability		Runtime stability and error safety.

📄 LicenseCopy Anchor Link

MIT © Ofri Peretz