Auditing NPM Dependencies

Auditing npm Dependencies

Overview

Modern Node.js applications pull in hundreds of transitive packages through a single npm install. The ratio of direct-to-transitive dependencies on a typical app is around 1:50 — install 30 packages, end up with 1,500. Every one of those packages can ship a CVE, get maintainer-takeover-attacked, or contain a typosquatted near-name package that someone slipped into your lockfile.

The published-CVE feed for npm is among the busiest in the ecosystem because the registry is shared, public, and trivially installable. npm audit queries the same advisory database GitHub's Dependabot uses, returning per-package vulnerability records with CVE ID, severity, affected version range, and fix-available version. Running it is free and fast; the friction is interpreting the output and deciding which findings actually block your release.

This skill standardizes that interpretation. It wraps npm audit --json, parses both the v1 (npm 6) and v2 (npm 7+) output shapes, maps npm's severity vocabulary to the shared Severity enum, and emits Findings in the canonical penetration-tester JSON shape so downstream tooling (CI gates, security dashboards, SOC2 evidence collection) gets uniform records regardless of which package manager surfaced them.

When the skill produces findings

Direct vs transitive matters: a CVE in lodash you require directly is fixable by upgrading your package.json. A CVE in lodash pulled in transitively through aws-sdk requires either upgrading aws-sdk to a version with a newer lodash floor, or pinning via overrides in your root package.json.

Prerequisites

• Node.js + npm installed on the host running the scan (npm 6+ supported; npm 7+ recommended for richer output)
• Target project directory containing package.json and at minimum one of package-lock.json, npm-shrinkwrap.json
• Network access to the npm registry (registry.npmjs.org by default)

Instructions

Step 1 — Identify the scan target

Locate the project directory. The scanner expects package.json at the directory root. Monorepos with multiple package.json files should be scanned per package; the scanner does not auto-traverse workspaces (use npm audit --workspaces separately for that case).

Step 2 — Run the audit

python3 ./scripts/audit_npm.py /path/to/node-project

Options:

Usage: audit_npm.py PATH [OPTIONS]

Options:
  --output FILE      Write findings to FILE (default: stdout)
  --format FMT       json | jsonl | markdown (default: markdown)
  --min-severity SEV (default: info)
  --include-dev      Audit `devDependencies` too (default: prod only)
  --no-cache         Pass --no-audit-cache to npm (slower; fresh data)
  --json-only        Print raw `npm audit --json` and exit (debug)

The scanner shells out to npm audit --json in the target directory, parses the output, deduplicates per-CVE across direct and transitive paths, and emits one Finding per CVE.

Step 3 — Interpret findings

CRITICAL / HIGH = block the release. Either bump the vulnerable package to the fix version (most common), or apply an npm overrides entry if the transitive dep can't be reached through a parent bump.

MEDIUM / LOW = file a remediation ticket but don't block. These often require waiting for the upstream maintainer to ship a fix.

INFO = log only. Informational advisories sometimes flag deprecated packages without an active vulnerability.

Step 4 — Remediation

For a CVE in a DIRECT dep:

1. Run npm audit fix — npm attempts a non-breaking upgrade.
2. If npm audit fix says "requires manual review" (semver-major bump), evaluate the breaking changes and decide whether to upgrade or accept the risk. Document the decision.
3. Pin the resolved version in package-lock.json; commit the diff.

For a CVE in a TRANSITIVE dep:

1. Identify the path: npm ls <vulnerable-package> shows which parent(s) pull it in.

2. Check whether bumping the parent picks up the fix: npm view <parent> dependencies lists the parent's declared range.

3. If parent has a newer version that floors the vulnerable dep above the fix-version, upgrade the parent.

4. Otherwise add an overrides block in your root package.json:

   "overrides": {
     "<vulnerable-package>": "<fix-version>"
   }
   

   This requires npm 8.3+ and forces the resolution. Document why you're overriding — overrides are easy to forget about.

For a CVE with NO fix available:

1. Subscribe to the GitHub Security Advisory for that CVE.
2. If exploitable in your usage context, replace the package or vendor it with a private patch.
3. Document the exception with a date for re-evaluation.

Examples

Example 1 — Pre-merge gate

python3 ./scripts/audit_npm.py . --min-severity high --format json --output npm-audit.json
jq -e '. == []' npm-audit.json || { echo "High/critical npm CVE — fix before merge"; exit 1; }

Example 2 — CI scan on every push

- name: npm dependency audit
  run: |
    python3 plugins/security/penetration-tester/skills/auditing-npm-dependencies/scripts/audit_npm.py \
        . --min-severity high --format markdown --output npm-audit.md
- name: Upload audit
  uses: actions/upload-artifact@v4
  with:
    name: npm-audit
    path: npm-audit.md

Example 3 — SOC2 evidence collection

python3 ./scripts/audit_npm.py . --include-dev --no-cache --format json \
    --output evidence/CC7-npm-audit-$(date +%Y%m%d).json

--include-dev is important for SOC2 evidence: auditors want the full picture, not just production deps. --no-cache ensures the evidence reflects current advisory data, not yesterday's cache.

Output

JSON / JSONL / Markdown per lib/report.py. Exit codes: 0 clean, 1 high/critical, 2 error.

Each Finding includes:

• id — synthesized as npm-audit::<cve-id> (or npm-audit::<advisory-id> when no CVE assigned)
• severity — CRITICAL / HIGH / MEDIUM / LOW / INFO
• category — dependency-vulnerability
• summary — short CVE title
• evidence — affected package, affected version range, fix version (if any), dependency path
• references — GHSA URL, CVE URL, npm advisory URL

Error Handling

• npm not installed → exits 2 with operational error advising the operator to install Node.js.
• No package.json → exits 2 with "target is not a Node project" error.
• npm registry unreachable → emits an INFO Finding documenting the outage and exits 0 (no actionable security finding).
• npm audit returns non-JSON garbage → emits an INFO Finding and exits 2. Sometimes happens with corrupt npm cache; advise the operator to run npm cache clean --force and retry.
• Lockfile out of sync with package.json → npm warns and may produce partial results; the scanner emits an INFO Finding flagging the desync and proceeds with whatever data npm returns.

Resources

• references/THEORY.md — Why npm's dependency graph is the largest CVE surface in modern software, history of npm supply-chain attacks (event-stream, ua-parser-js, color.js, node-ipc), direct-vs-transitive remediation theory, when overrides are safe, npm audit v1 vs v2 output schema diff
• references/PLAYBOOK.md — Per-runtime remediation patterns (frontend webpack/vite, Node server, Electron desktop, Lambda), parent-bump decision matrix, override-block templates, GitHub Dependabot integration, SOC2 evidence retention policy

Source: jeremylongshore/claude-code-plugins-plus-skills → skills/.curated/auditing-npm-dependencies/SKILL.md

Also appears in: jeremylongshore/claude-code-plugins-plus-skills/plugins/security/penetration-tester/skills/auditing-npm-dependencies/SKILL.md