io.github.Hookwarden/mcp

npx hookwarden scan ./your-app

No traffic leaves your machine. No telemetry. No SaaS sign-up required.

📖 Full documentation: docs.hookwarden.dev

Found in the wild

Every Sunday at 22:00 UTC, this repo's CI runs hookwarden against 45 popular open-source projects — currently cal.com, documenso, formbricks, twenty, plane, unkey, typebot, papermark (full target list, combined ★190k+) — to prove the scanner works on real production code.

Latest sweep — 2026-06-09 · 20/45 projects clean (zero critical/high)

These are bugs in the webhook handlers that receive provider events — flaws in the integrating projects' integration code, not in the providers' own SDKs or services.

Coverage note: the engine couldn't parse 238 files across the corpus (broken syntax or language features the parser doesn't model). Those are scan-coverage diagnostics — not handler bugs — and are excluded from the table above.

Hookwarden checks 11 rule classes across 21 providers — most of the corpus handles webhooks correctly, hence the short list. The full rule catalog lives in the docs.

Per-target findings are never published before responsible disclosure — see methodology. To run the same scan against your own code:

npx hookwarden scan ./your-app

Why

Every dollar of fraud that flows through a webhook starts with a verification bug — and verification bugs hide in plain sight.

A handler that accepts an unsigned payload, compares HMACs with ==, or skips the signature check on a ?test=true path silently routes attacker traffic into your business logic. The bug is one line in a 50K-line app, and it looks plausible — not the shape general-purpose SAST tools are tuned to flag. They were built for SQL injection and prototype pollution; webhook verification falls between their default rule packs.

hookwarden does one thing. It walks your repo, parses every webhook handler across 11 frameworks, and labels each one verified, not-verified, or manual-review — with the exact file, line, and a fix quoted from provider docs. The catalog (21 named providers — Stripe, GitHub, Shopify, Slack, Twilio, Square, Sentry, Zendesk, DocuSign, PagerDuty, Notion, Auth0, HubSpot, Intercom, Linear, Zoom, Calendly, Bitbucket, Mailchimp, Postmark, plus Standard Webhooks conformant providers like Clerk, Resend, Mux) encodes signature quirks no generic scanner has the surface area to know: Stripe's 5-minute timestamp tolerance, Slack's v0:${ts}:${body} scheme, Twilio's SHA-1 outlier.

The three-state verdict is not a hedge. manual-review is what you get when hookwarden can't prove safety or unsafety from the source alone — a handler inside a middleware chain the analyzer couldn't unroll, say. It's how the false-positive rate stays honest (<5%, measured against a 200-repo OSS corpus). A tool that reports every gray area as a bug isn't a security tool; it's noise. → How the verdict works

Install

npx hookwarden scan .   # works everywhere, no install

hookwarden is a CLI, not a library — run it with npx hookwarden scan . or install globally with npm i -g hookwarden. (The plain npm i hookwarden that npm auto-suggests on the package page installs it as a local dependency, which isn't what you want for a command-line tool.)

Or install natively:

Node 22+ is required for the npm/npx/macOS-brew paths; the standalone binaries (Linux x64/arm64, Windows x64) bundle the runtime. Direct binary downloads are intentionally unsigned (Gatekeeper / SmartScreen will warn) — prefer brew / scoop / npm / pip, which verify by SHA-256. → Install guide

Update

hookwarden --version   # check what you have

Rule pack versions move with the CLI (engine, rules, and CLI ship as a fixed group — 0.7.5 everywhere). Pin in CI with npx hookwarden@0.7.5 scan . if you want byte-stable verdicts across runs.

Quickstart

# Scan — no install required
npx hookwarden scan ./your-app

# Fail CI on high+ findings, machine-readable output
npx hookwarden scan ./your-app --fail-on high --format json
# Exit codes: 0 clean · 1 findings at threshold · 2 engine error · 3 config error · 4 parse coverage below floor

# Adopt on a non-greenfield repo — accept existing findings, gate only NEW ones
npx hookwarden scan ./your-app --baseline write
npx hookwarden scan ./your-app --fail-on high

# List every detected webhook handler (no rules run) — useful for audits
npx hookwarden inventory ./your-app

--diff-only, --provider stripe,github (phased rollout), --include/--exclude globs, --strict-suppressions, repo-level hookwarden.config.yaml, and more: npx hookwarden --help and the CLI docs.

Git history scan (--history)

By default scan only looks at your working tree. --history also walks the git history — including files that were committed then deleted before HEAD — so a secret that was force-pushed away is still found. It's off by default and bounded to the last 1000 commits; narrow it with --since <ref|date>:

npx hookwarden scan --history                 # last 1000 commits
npx hookwarden scan --history --since v1.0.0   # since a tag/ref
npx hookwarden scan --history --since 2026-01-01

--history is fully open-source and never requires a token.

Live verification (--verify-secrets)

--verify-secrets checks whether a leaked API-key-class credential is still alive by making a single read-only call to the secret's own provider (Stripe / GitHub) directly from your machine — hookwarden never sees the secret. A live leak is escalated to critical; a dead (rotated/revoked) one is downgraded to info. It's paid (team tier), off by default, and explicit opt-in only.

# Mint a token from the dashboard (Settings → CLI tokens) on a team workspace:
HOOKWARDEN_TOKEN=hw_… npx hookwarden scan --verify-secrets

• The credential is held in-memory only and redacted in all output.
• The entitlement check transmits only your token — never the secret.
• A webhook signing secret (whsec_, GitHub webhook secret) is always reported unverified — no provider can confirm a signing secret's liveness.
• Without a valid HOOKWARDEN_TOKEN, findings are reported unverified and no provider call is made.

Auto-fix

hookwarden doesn't just name the fix — it applies it. The fix subcommand mechanically rewrites the safety: safe subset across JS/TS, Python, PHP, and Go (covering timing-unsafe comparisons → crypto.timingSafeEqual / hmac.compare_digest / hash_equals, and raw-body misuse). The other 188 rules are architectural and emit per-finding fix prose instead.

npx hookwarden fix ./your-app           # dry-run — prints a unified diff, writes nothing
npx hookwarden fix ./your-app --write   # atomic staging, re-scan, then rename into place

Every rewrite lands in a staging dir and is re-scanned before replacing the original; the fixer never edits inside strings or comments. → hookwarden fix · Safety levels

Real output

Captured verbatim — each line is what you'll see in your terminal, not a mockup. One Express middleware bug produces three findings, because that single mistake violates three distinct invariants; fixing one (re-ordering the middleware) clears all three:

$ hookwarden scan ./your-app
× critical  server.js:10:1  stripe/express-middleware-ordering  not-verified
  Express webhook handler for Stripe has `express.json()` registered before the webhook route. JSON
  middleware consumes the request body; by the time the Stripe handler runs, the raw bytes used for
  HMAC are gone and `stripe.webhooks.constructEvent` cannot reproduce the signature.
  fix › register `express.json()` AFTER the webhook route, OR mount `express.raw(...)` on the path only.
  docs › https://docs.stripe.com/webhooks#verify-events
  refs › https://expressjs.com/en/guide/using-middleware.html
         https://www.svix.com/blog/common-failure-modes-for-webhook-signatures/

× critical  server.js:10:1  stripe/missing-signature-verification  not-verified
  Stripe webhook handler does not appear to verify the signature header before processing the event …

× critical  server.js:10:1  stripe/raw-body-misuse  not-verified
  Stripe webhook handler reads the signature header but does not appear to receive the body as raw bytes …

────────────
Found 3 critical · 0 high · 0 medium · 0 low · 0 info · 0 manual-review — 1 webhook handler across 1 file
Scanned in 3 ms · 1 / 1 candidates parsed (100.0% coverage)

The state column is the three-state verdict. Output is also available as byte-stable JSON and SARIF 2.1.0 (round-trips through GitHub Code Scanning, dedupes via partialFingerprints). → Output formats & JSON schema

Languages, frameworks & providers

4 languages · 15 frameworks · 21 providers · 230 rules · 100% cited. Every rule carries ≥1 external citation (CWE / RFC / Svix / Stripe spec) alongside the provider's own docs — auditors and reviewers can follow any finding back to a stable external source. JS/TS parse with Babel; Python, PHP, and Go with tree-sitter (WASM).

Every rule carries fix guidance quoted from the provider's canonical security docs. Full per-rule reference and coverage matrix: docs.hookwarden.dev/rules.

CI integration

# .github/workflows/hookwarden.yml
name: hookwarden
on: [pull_request, push]
permissions:
  contents: read
  pull-requests: write
  security-events: write
jobs:
  scan:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with: { fetch-depth: 0 }
      - uses: Hookwarden/hookwarden-action@v1
        with:
          fail-on: high

Uploads SARIF to Code Scanning automatically; findings appear as PR annotations. Raw-CLI + SARIF-upload recipe, exit-code matrix, and diff-only PR scans: → CI integration guide.

vs. other tools

hookwarden is specialized on purpose. The general-purpose scanners below are excellent — they're just not in this fight.

hookwarden is not a general-purpose SAST or DAST scanner — it won't find XSS, SQL injection, or memory-safety bugs, and it isn't trying to. Keep semgrep, CodeQL, or your DAST for those. Already running one? hookwarden is additive — it finds the one class of bug they weren't built to catch.

AI agents (Claude Code, Cursor, Continue)

@hookwarden/mcp is a Model Context Protocol server that gives AI coding agents the scan_handler tool. Paste in any webhook handler, get back the same 3-state verdict (verified / not-verified / manual-review) the CLI would emit — fully local, deterministic, no traffic leaves the agent's machine.

npx @hookwarden/mcp init           # auto-detects Claude Desktop / Cursor / Continue and writes the config

The rule pack is bundled inline, content-hashed, and version-pinned to the engine — scan_handler cross-checks both on every call and fails loudly on drift. → @hookwarden/mcp on npm

Architecture

A pnpm monorepo with a strict, CI-enforced dependency boundary: the engine is pure-functional (no I/O, no filesystem, no network), so the same engine runs in the CLI, in CI, in the MCP server, and — eventually — in a browser playground without modification.

dependency-cruiser enforces the engine's I/O boundary in every PR.

Roadmap

• ✅ v0.8 — @hookwarden/mcp developer preview (Model Context Protocol server exposing scan_handler to Claude Code, Cursor, Continue, and the Anthropic Agent SDK — pasted handler code returns a 3-state verdict locally, zero-network, deterministic). → MCP server
• ✅ v0.7.2 — references visible in output (text renderer gains a refs › block per finding; JSON envelope gains scan.findings[].references: string[]. v0.7.1 cited every rule; v0.7.2 makes citations actually visible to scan consumers).
• ✅ v0.7.1 — rule-pack polish (references backfilled on 142 grandfathered rules → 230 cited; test-path severity overrides on 219 rules → test fixtures no longer false-fire as critical/high).
• ✅ v0.7 — Rule Depth (5 new rule classes: VAS / BYP / ERS / LEAK / RPL families across 21 providers; rule pack grew 142 → 230).
• ✅ v0.6 — rule-pack expansion (15 new provider rule packs incl. Zendesk, DocuSign, PagerDuty, Bitbucket, Notion, Calendly, Zoom; Standard Webhooks spec sweep covers Clerk, Resend, Mux, Lob, etc.; CVE-2026-41432 Stripe empty-secret detector).
• ✅ v0.5 — hookwarden fix auto-remediation (mechanical AST rewrites, safe/manual-only per rule).
• ✅ v0.4 — PHP support (Laravel, Symfony, Slim, vanilla) + --provider filter for phased rollout.

Contributing

Rule-pack PRs are the highest-value contribution — adding a provider is a catalog edit plus N rule YAMLs, no new TypeScript in most cases. See the existing 21 in packages/rules/rules/ as worked examples, and CONTRIBUTING.md.

pnpm install && pnpm -r build && pnpm -r test

Bug reports & feature requests: open an issue. Docs: docs.hookwarden.dev · hookwarden.dev.

To add yourself after a merged PR, comment @all-contributors please add @<username> for <contribution>.

Star history

License

Apache 2.0 — see LICENSE. The CLI, engine, and rule packs are open source and will stay that way. A separate closed-source SaaS tier handles continuous monitoring, secret-leak scanning, automated rotation, and SOC 2 evidence export — hookwarden.dev.