mcp-audit

npm audit for MCP servers. Point it at an MCP server and get a security grade (A–F) covering missing auth, SSRF surface, high-privilege tools, prompt-injection-prone tool descriptions, and leaked secrets.

Why this exists (2026 data): of ~7,000 public MCP servers, 41% require no auth, 36.7% expose an SSRF surface, only 8.5% use OAuth, and 30+ CVEs were filed in a single 60-day window. Server count is saturated (22k+ servers); security posture is not. Other tools (e.g. Invariant's mcp-scan) inspect a single server deeply — mcpaudit adds registry-wide batch auditing: point it at the official MCP Registry and grade the whole ecosystem at once.

npm i -g @andreolf/mcpaudit    # then: mcpaudit <url>
# or zero-install:  npx @andreolf/mcpaudit <url>

Is it safe to run? Yes by design: mcpaudit sends only a read-only initialize + tools/list handshake and inspects the declared tools. It never executes a scanned server's code unless you explicitly pass --allow-exec to spawn a local/npm server.

⚠️ Heuristic scanner. Findings describe surface (e.g. "no auth", "exposes a URL-fetching tool"), not proven exploits — a clean report is not a security guarantee. Scan only servers you're authorized to test, and disclose findings responsibly. See SECURITY.md.

Usage

Scan a remote server (Streamable HTTP):

node bin/mcp-audit.js https://example.com/mcp
node bin/mcp-audit.js https://example.com/mcp --header "Authorization: Bearer $TOKEN" --json

Scan a published server (spawned via npx -y <package>):

node bin/mcp-audit.js --npm @modelcontextprotocol/server-filesystem --timeout 20000

Scan a local server started by a command (stdio):

node bin/mcp-audit.js --cmd "node my-server.js"

Requires Node 18+ (uses global fetch). Zero dependencies. Install: npm i -g @andreolf/mcpaudit then mcpaudit <url> — or npx @andreolf/mcpaudit <url>.

Exit codes: 0 clean · 1 critical/high finding · 2 couldn't scan / bad usage. CI-friendly.

Related MCP server: mcp-security-audit

Batch mode (the launch audit)

Scan many servers and get a worst-first leaderboard + the aggregate stats for a launch post:

node bin/mcp-audit-batch.js targets.txt --out audit.md

targets.txt is one target per line (https://…, npm:<package>, or cmd:<command>; # comments allowed).

⚠️ Safety: scanning an npm:/cmd: server runs that server's code on your machine. Batch mode is HTTP-only by default and SKIPS local/npm targets unless you pass --allow-exec — do that only inside a sandbox/container you trust. Mass-running untrusted packages is remote-code-execution exposure.

Output includes the headline numbers ("X% of reachable HTTP servers accept initialize with no auth") that become the launch thread.

The full launch pipeline

Pull targets from the official MCP Registry (discovery only — never executes a server), then audit them:

node bin/mcp-audit-fetch.js --max 300 --out targets.txt   # HTTP remotes = safe to scan
node bin/mcp-audit-batch.js targets.txt --concurrency 8 --out audit.md

mcpaudit-fetch emits registry HTTP endpoints as scannable lines and npm packages as commented lines (opt in with --include-npm, then --allow-exec in a sandbox). A real run of the first 30 registry servers found 50% accept initialize with no auth — the kind of number the launch post is built on.

Use in CI (GitHub Action)

Gate your MCP server's security on every PR. Start your server, then point the action at it:

- name: Start my MCP server
  run: node my-server.js &   # or docker run ..., then wait for it to be ready

- name: Security-audit the MCP server
  uses: andreolf/mcp-audit@v1
  with:
    url: http://localhost:3000/mcp
    fail-on: D                      # fail the job on grade D or worse (default: F)
    # header: "Authorization: Bearer ${{ secrets.MCP_TOKEN }}"   # optional

The job prints an A–F grade and the findings, and fails if the grade is at or below fail-on. Nothing is executed on the scanned server — it only sends a read-only handshake.

Test

npm test   # spawns the mock insecure server (stdio + batch) and asserts findings — 12 checks

What it checks (starter heuristics — expand these)

• no-auth — server accepts initialize with no credentials (critical)

• ssrf-surface — tools that take URLs / make outbound requests (high)

• high-privilege-tool — exec/shell/delete/write-file style tools (high)

• injection-in-description — override/injection phrasing in tool descriptions (medium)

• leaked-secret — token/key-shaped strings in tool metadata (critical)

Architecture

bin/mcp-audit.js   CLI entry (arg parsing, exit codes for CI)
src/scan.js        orchestrator
src/mcpClient.js   MCP Streamable-HTTP transport: initialize + tools/list
src/checks.js      heuristic security checks -> findings
src/report.js      grading (A–F), badge, Markdown/JSON output

Roadmap (turn this skeleton into the viral thing)

1. ✅ stdio + npm transports — scan local (--cmd) and published (--npm, via npx) servers, not just remote URLs. This unlocks scanning the registry's top servers for the launch audit. (PyPI/uvx equivalent is a small follow-up.)

2. Static-key vs OAuth detection — inspect the auth challenge / token format.

3. Deeper SSRF probe — actually call fetch-style tools against a canary internal URL in a sandbox.

4. ✅ Batch mode + leaderboard — mcpaudit-batch targets.txt → ranked report + headline stats. That ranked report is the launch artifact: "We audited the 200 most-installed MCP servers."

5. ✅ Registry fetcher (mcpaudit-fetch) — pulls HTTP targets from the official MCP Registry (discovery only, never executes). npm packages emitted commented-out. --include-npm to opt in.

6. Embeddable badge — MCP Security: A shields.io-style badge servers add to their README (2026 ranking signal, and free distribution for you).

7. Registry presence — list on mcp.so, smithery.ai, glama.ai, PulseMCP, official MCP Registry, and PR to punkpeye/awesome-mcp-servers. Prepare one metadata pack, submit to all.

License

MIT