pkgxray — pre-install security for npm packages, MCP servers, and AI agents.
Use local, zero-dependency package static analysis to inspect npm packages and
Model Context Protocol (MCP) servers before installation or connection. pkgxray
reports cited SAFE
, REVIEW
, or BLOCK
evidence without executing package code during normal scans.
Static analysis · Supply-chain intelligence · Prompt-injection detection ·
MCP security · SAFE
/ REVIEW
/ BLOCK
Real runs: guard clears express@4.21.0, then blocks a sample modeled on the 2024 @solana/web3.js compromise.
▶ 60-second walkthrough
npx --yes pkgxray@1.0.4 guard npm:express@4.21.0
This downloads pkgxray through npm's temporary npx
cache, stages the target
tarball in quarantine, and performs the static and supply-chain checks. It does
not globally install pkgxray, run npm install
, execute lifecycle scripts, or execute package code.
Decision: **SAFE**
Grade: **A+** (99/100)
No high- or medium-risk indicators were found in the provided evidence.
Notes:
- **INFO npm-vs-github-clean** — npm tarball matches the linked GitHub repo
at the published version. (15/16 files match GitHub @4.21.0)
…
Real output, abridged. A BLOCK verdict instead lists every finding with the file and evidence that produced it.
Point it at a package, get a verdict with cited evidence — before a single
line of that package runs. guard
stages the package in a sandboxed
quarantine, audits the staged copy, and only promotes it when policy allows.
It never runs npm install
, lifecycle scripts, build steps, or package code.
| Verdict | Exit | Meaning |
|---|---|---|
SAFE |
||
0 |
||
| No high- or medium-risk indicators were found; default policy permits promotion. | ||
REVIEW |
||
3 |
||
| Evidence is incomplete or a privileged capability needs human review. | ||
BLOCK |
||
2 |
||
| High-severity cited evidence requires rejection or deep investigation. |
SAFE
is not a proof that a package is harmless; static analysis cannot see a payload downloaded only at runtime. See the threat model.
From a repository checkout:
npx --yes pkgxray@1.0.4 --file examples/onboarding-malicious.json --format markdown
The fixture contains inert source text that models a split-string SSH-key read
and network exfiltration. It is never executed. The command returns BLOCK
(exit 2
) and cites the matching file and evidence.
Scan pull requests and schedule dependency rechecks.Expose pkgxray's tools to an MCP-capable coding agent.Evaluate the experimental Hookshot install gate.
AI coding assistants install packages and connect to MCP servers at machine speed, often without a human ever reading the code. Sonatype reported 454,648 newly identified malicious open-source packages across monitored ecosystems in 2025. Its Q4 report counted 394,877 in that quarter and said 99.8% of Q4 malware originated from npm (annual figure; Q4 scope). Traditional antivirus inspects what executes; pkgxray inspects what gets installed.
npm audit
and OSV-Scanner answer an essential question — does this package have a known CVE? — and pkgxray asks it too (via OSV, before anything downloads). But a freshly trojaned package has no CVE yet, so pkgxray also analyzes trust: what the code actually does, whether the published npm artifact matches the tagged GitHub source, whether the provenance attestation is consistent with the claimed repository, and whether the docs carry a prompt-injection payload aimed at the agent reading them.
It is intentionally conservative: verdicts come from deterministic heuristics (no LLM in the verdict path, so injected text can't steer them), only citable evidence is reported, and the zero-heuristic-false-block calibration on the top-1000 most-downloaded packages is regression-gated in CI. That claim is scoped to the most-installed set — it is not a claim of zero false blocks on every package; the newer MCP/agent-tooling ecosystem is over-blocked and being reconciled per-case (details).
| Threat | Coverage | How pkgxray sees it |
|---|---|---|
| Credential theft | ✅ | reads of .ssh / .aws / .npmrc / .env / keychains / wallets, incl. split-fragment paths (".s"+"sh" ) |
| Prompt injection | ✅ | tiered detection in docs, comments, metadata; deterministic verdict path can't be steered |
| Unicode smuggling | ✅ | invisible tag-block characters + Trojan Source bidi / zero-width |
| Base64 payloads | ✅ | encoded envelopes in docs/comments; blobs decoded into computed-arg eval / new Function / child_process |
| Exfiltration & s | ✅ | cross-file correlation: stage-2 s, `curl |
| Persistence | ✅ | writes to shell rc files, cron, launch agents |
| Obfuscation | ✅ | packed blob + computed-arg execution; minification alone is deliberately not flagged |
| Known CVEs | ✅ | OSV batch pre-check before download; never mutable by config |
| Trojaned updates / maintainer takeover | ✅ | recheck verdict-drift + version-drift monitoring |
| Artifact divergence | ✅ | published npm tarball diffed against the tagged GitHub source |
| MCP capability abuse | ✅ | capability-surface mismatch in the manifest audit (a get_weather that also takes a command ) |
| Runtime tool drift | ✅ | mcp-proxy re-audits on tools/list_changed ; pinned-manifest drift is denied |
| Sequence-level tool-call chains | ◑ | mcp-proxy gates each call and scans results; no cross-call flow analysis — |
| Dependency confusion / typosquats | ◑ | callback beacons, repo-mismatch and provenance-mismatch signals; no name-similarity heuristic |
✅ detected · ◑ partial / indirect
Known blind spot: pkgxray reasons about bytes in the tarball. A package that downloads its real payload after install can ship a clean tree — pkgxray flags the capability when its shape is unambiguous, but pair it with runtime sandboxing when that risk matters. Full analysis: docs/threat-model.md.
Continuous monitoring—diffs installed deps against a stored verdict baseline and pre-vets newer versionspkgxray recheck
MCP vetting—pkgxray mcp
audits a server's tool manifest before you connect;--pin
/--recheck
catch the rug-pull;pkgxray-mcp
gives any agent the audit tools directlyRuntime gate—wraps a live MCP server on the wire: denied tools stripped, ~0.05 µs per-call verdict, injection scan of tool resultspkgxray mcp-proxy
Install gate— ahookshothook runsguard
on every package an agent tries to install, across Claude Code, Cursor, Windsurf, Factory Droid, and Codex ()examples/hookshot/
Policy engine— one.pkgxray.json
read by every surface; tighten freely, every loosening is printed; CVEs can never be allowed away; fail closedOpt-in behavioral canary—runs lifecycle scripts in an OS sandbox with decoy credentials; it canpkgxray canary
confirmmalice, nevercleara package
| Verdict | Meaning | You should |
|---|---|---|
🟢 SAFE |
||
| No high- or medium-risk indicators. | Install. Only safe promotes out of quarantine by default. |
|
🟡 REVIEW |
||
| Incomplete evidence, or a privileged capability that needs a human. | Inspect the quarantined copy before promoting. | |
🔴 BLOCK |
||
| High-severity, cited evidence. | Do not install. Every finding names the file and evidence. |
Exit codes are stable and CI-friendly: ** 0** safe/allow ·
block ·
2
review. The full signal-to-severity mapping is in the
3
Vet an npm package before installing
pkgxray guard npm:some-package@1.2.3 [--format json]
pkgxray guard ./ext --promote-to ./approved/ext # local dir, promote if policy allows
Vet an MCP server before connecting — full guide: docs/mcp.md
pkgxray mcp --package npm:some-mcp-server@1.4.2 npx some-mcp-server
pkgxray mcp --recheck npx some-mcp-server # catch the rug-pull
Enforce in CI/CD
pkgxray audit package-lock.json [--deep] # also: yarn.lock, pnpm-lock.yaml, package.json
npx pkgxray recheck package-lock.json # scheduled: exits non-zero only on a regression
A ready-made GitHub Actions integration
and the self-hostable cache server (PKGXRAY_CACHE_URL
) are documented in the reference.
Guard AI coding agents
pkgxray is published on the MCP Registry
as io.github.adamsjack711-ux/pkgxray
. Add it to any MCP client — locally
installed (pkgxray-mcp
) or zero-install via npx
:
{
"mcpServers": {
"pkgxray": {
"command": "npx",
"args": ["--yes", "--package", "pkgxray@1.0.4", "pkgxray-mcp"],
"env": { "PKGXRAY_MCP_ALLOWED_ROOTS": "/absolute/path/to/project" }
}
}
}
The MCP guide explains the operator-owned filesystem boundary. Product-specific setup is in the coding-agent integration guide. Gate installs with the Hookshot integration and wrap MCP servers with pkgxray mcp-proxy.
One optional .pkgxray.json
, read by every surface. Zero config means maximum strictness.
{
"policy": "safe-only", // or "allow-review" (a loosening — warns)
"failOn": "review", // CI exit threshold
"scanErrorPolicy": "fail-closed", // a scan that errors → review, never safe
"allow": [
{ "pkg": "left-pad@1.3.0", "sha256": "e0b0…",
"reason": "reviewed 2026-07", "expires": "2026-10-01" }
]
}
Precedence, mute
/ mcp
blocks, and enforced invariants:
docs/configuration.md ·
.pkgxray.example.json
The 60-second walkthrough — the SAFE run, the blocked trojan with its exit code, then a lockfile audit:
pkgxray-demo.mp4 #
All captures are real runs — reproduction steps in
docs/screenshots/
, which also shows the
MCP proxy, hookshot install gate, and browser extension in action.npm audit
and OSV-Scanner match dependencies against known CVEs — a different question, answered well. pkgxray is designed to run alongside them, not replace them (it queries OSV itself, before anything downloads). The comparison that matters is against tools in the same lane — behavioral supply-chain vetting:
| Capability | Socket.dev | OpenSSF Package Analysis | Cisco MCP Scanner | pkgxray |
|---|---|---|---|---|
| Fully local, zero-dependency, no account or cloud upload | — ¹ | ◑ ² | ◑ ³ | ✅ |
| Static behavior analysis of package code | ✅ | ✅ | ✅ | ✅ |
| Sandboxed execution (dynamic analysis) | — | ✅ ⁴ | ◑ (optional Docker) | ◑ (opt-in canary ) ⁴ |
| npm ↔ GitHub artifact divergence | unknown | — | — | ✅ |
| Deterministic verdict path — no LLM an injection can steer | — ⁵ | ✅ | ◑ ⁵ | ✅ |
| Pre-install gate with a quarantined copy to review | ◑ ⁶ | — | — | ✅ |
| MCP server vetting before connect | — ⁷ | — | ✅ | ✅ |
| Per-call runtime gating of live MCP traffic | — | — | — ⁸ | ✅ (mcp-proxy ) |
| Verdict-drift monitoring vs. a stored baseline | ✅ (cloud-side) | — | — | ✅ (local recheck ) |
Comparison made 2026-07-21 against each tool's public documentation; unknown means not publicly documented — not verified either way.
¹ Socket's analysis runs in its cloud; Socket Firewall needs no account but consults Socket's hosted intelligence on every install. ² Open source and self-hostable, but built as a registry-scale analysis pipeline (Docker/gVisor), not an install-time developer gate. ³ The YARA analyzer runs locally; the LLM-as-judge and Cisco AI Defense analyzers require API keys. ⁴ Both detonate packages in an OS sandbox. pkgxray's opt-in
canary
require
(flatmap-stream) shape that is pkgxray's stated blind spotis triggered and observed. Egress is now kernel-confined on both platforms:
sandbox-exec
on macOS and, on Linux with bubblewrap
iproute2
, a private
network namespace (bwrap+netns
) where a raw-socket dial that bypasses the
proxy is refused by the kernel (ENETUNREACH
) while proxied egress is still captured. That tier engages only after a runtime self-test proves itin the environment (verify with
node scripts/verify-netns-confinement.js
); absent the tooling it falls back to observe-only and says so. Still ◑ — not for a confinement gap, but by design: canary is opt-in and confirm-only (it proves malice, never clears a package) and detonates without the package's dependencies installed, whereas OpenSSF Package Analysis runs registry-scale and default-on. Run them as complements — pkgxray before install, full dynamic analysis where that risk matters. ⁵ Socket's LLM-based code inspection is a headline feature (“AI-detected potential malware”, human-confirmed); Cisco's YARA-only mode is deterministic, its LLM analyzer is not. ⁶ Socket Firewall blocks risky packages at install time; it does not stage a quarantined copy for human review. ⁷ Socket's MCP offering exposes its package-scoring API to agents; it does not vet arbitrary MCP servers at connect time. ⁸ Cisco MCP Scanner is analysis-only per its docs — it does not proxy or gate live MCP traffic.Acquisition (OSV pre-check → fetch) → sandboxed quarantine → static analysis → policy → verdict. The same engine backs every surface: CLI, MCP server, runtime proxy, install hook, browser extension, and CI cache server. Principles: never execute untrusted code · citable evidence only · minimize false positives · fail closed · zero runtime dependencies.
Details: docs/architecture.md · docs/design.md
Local static analysis: ~25 ms— a full guard ofexpress
is ~1.3–1.5 s cold-cache, almost all network round-trips (Apple M1, Node 26)Known-vulnerable packages block at the OSV pre-check, before download** Calibration**(precision, recall, the 0-heuristic-false-block gate on the top-1000 most-downloaded —scope) is measured by a committedbenchmark corpusthat fails CI when it regresses
Full numbers: docs/reference.md#performance · methodology: docs/benchmark.md
| Doc | What it covers |
|---|---|
threat-model.mdmcp.mdmcp-registry.mdconfiguration.md.pkgxray.json
schema and invariantsreference.mdrecheck
, JSON output, cache serverbenchmark.mdcompatibility.mdjson-schema.md--format json
schemaStart at the documentation index. Longer-term plans: project status, adoption playbook, and GitHub issues.
npm test # zero-dep node --test suite
npm run benchmark # calibration corpus: precision/recall + 0-false-block gate
npm run build:browser # build the MV3 browser extension
Contributions are welcome; read CONTRIBUTING.md and the Code of Conduct before opening a pull request.
Releases are published to npm with provenance (SLSA attestation), gated on the test suite, the calibration benchmark, and pkgxray's own supply-chain guard. To report a vulnerability in pkgxray itself, see SECURITY.md.