create-mastra@1.28.0

Create Mastra apps with one command

AI Security Review

scanned 1mo ago · by lpm-firewall-ai

This is not malicious install-hook abuse, but its default, user-triggered installation of agent skills is a concrete guarded extension-lifecycle risk. The telemetry is a privacy concern but does not establish credential exfiltration.

Static reason

High-risk behavior combination matched malicious policy.

Trigger

A user runs the create-mastra CLI without --no-skills or telemetry opt-out.

Impact

A remote skills package can modify detected agent extension surfaces; telemetry exposes device and environment metadata.

Mechanism

Default agent-skill installation through npx plus telemetry reporting.

AI rationale

Evidence

dist/index.js

Network endpoints1

us.posthog.com

Decision evidence

public snapshot

AI called this Suspicious at 86.0% confidence as Dangerous Capability with medium false-positive risk.

Evidence for warning

Running the CLI starts telemetry that reports host and system metadata to a hardcoded PostHog host unless disabled.
The generated-project setup enables skills by default, detects installed coding agents, and runs an unattended npx skills add command for mastra-ai/skills.
The manifest exposes dist/index.js as the create-mastra executable, making this behavior reachable when the user runs the CLI.

Evidence against

package.json has no preinstall, install, or postinstall lifecycle hook.
Credential persistence and platform token writes occur only in the interactive, opt-in observability flow.
The inspected command creates a project and installs first-party skills; no secret harvesting, destructive action, or hidden payload was found.

Behavioral surface

Source

ChildProcessCryptoEnvironmentVarsFilesystemNetworkShell

Supply chain

HighEntropyStringsTelemetry

Source & flagged code

9 flagged

dist/index.jsView file

Lines 1-31javascript

1#! /usr/bin/env node

2import { InvalidArgumentError, Command } from 'commander';

3import { randomBytes, randomUUID } from 'node:crypto';

4import fs, { readFileSync, statSync, appendFileSync, writeFileSync, createWriteStream, createReadStream, existsSync, mkdirSync, constants as constants$2 } from 'node:fs';

5import os, { homedir, release, constants as constants$1 } from 'node:os';

6import path, { join, dirname } from 'node:path';

7import * as fsPromises from 'node:fs/promises';

8import fsPromises__default, { readFile, mkdir, writeFile, chmod } from 'node:fs/promises';

9import require$$0, { execFileSync, ChildProcess, execFile, spawnSync, spawn } from 'node:child_process';

10import { createServer } from 'node:http';

High

Child Process

Package source references child process execution.

dist/index.jsView on unpkg · L8

11import require$$4, { styleText, debuglog, stripVTControlCharacters, inspect, promisify, callbackify, aborted } from 'node:util';

12import process$2, { stdout, stdin, platform, hrtime, execPath, execArgv } from 'node:process';

13import * as l from 'node:readline';

Critical

Hardcoded Runtime Data Exfiltration

Source sends credentials or rich application records to a package-controlled external receiver enabled by default.

dist/index.jsView on unpkg · L8

Critical

Trigger Reachable Dangerous Capability

A package entrypoint or install-time lifecycle script reaches a source file with blocking dangerous behavior.

dist/index.jsView on unpkg · L8

High

Shell

Package source references shell execution.

dist/index.jsView on unpkg · L11

High

Sandbox Evasion Gated Capability

Source gates dangerous network, credential, or execution behavior behind CI, host, platform, time, or geo fingerprint checks.

dist/index.jsView on unpkg · L8

14import l__default from 'node:readline';

15import tty, { ReadStream } from 'node:tty';

16import { PostHog } from 'posthog-node';

17import { fileURLToPath } from 'node:url';

18import { StringDecoder } from 'node:string_decoder';

19import { setTimeout as setTimeout$1, scheduler, setImmediate } from 'node:timers/promises';

20import { once, addAbortListener, EventEmitter, on, setMaxListeners } from 'node:events';

21import { serialize } from 'node:v8';

22import { Transform, getDefaultHighWaterMark, Duplex, Writable, Readable, PassThrough } from 'node:stream';

23import { Buffer as Buffer$1 } from 'node:buffer';

24import { finished } from 'node:stream/promises';

25import { x } from 'tinyexec';

27const PATH_PARAM_RE = /\{[^{}]+\}/g;

28const supportsRequestInitExt = () => {

29 return typeof process === "object" && Number.parseInt(process?.versions?.node?.substring(0, 2)) >= 18 && process.versions.undici;

30};

31function randomID() {

Lines 10317-10357javascript

10317// Wraps `finished(stream)` to handle the following case:

10318// - When the subprocess exits, Node.js automatically calls `subprocess.stdin.destroy()`, which we need to ignore.

10319// - However, we still need to throw if `subprocess.stdin.destroy()` is called before subprocess exit.

10320const waitForStream = async (stream, fdNumber, streamInfo, {isSameDirection, stopOnExit = false

Lines 15209-15249javascript

15209 });

15210 } catch (gitError) {

15211 if (signal?.aborted) signal.throwIfAborted();

15212 throw new Error(`Failed to clone repository: ${gitError instanceof Error ? gitError.

•Manifest-reachable source captures an API credential, sends it to a fixed unofficial gateway, and persists that redirection in agent or shell configuration. dist/index.js: import fs, { readFileSync, statSync, appendFileSync, writeFileSync, createWriteStream, createReadStream, existsSync, mkdirSync, constants as constants$2 } from 'node:fs'; import fsPromises__default, { readFile, mkdir, writeFile, chmod } from 'node:fs/promises'; import * as l from 'node:readline'; import l__default from 'node:readline'; baseUrl = "", baseUrl = removeTrailingSlash(baseUrl); baseUrl: localBaseUrl, let finalBaseUrl = baseUrl;

High

Credential Redirect Persistence

Manifest-reachable source sends a prompted API credential to a fixed unofficial gateway and persists the redirection.

dist/index.jsView on unpkg

Source & flagged code

9 flagged · loading source

dist/index.jsView file

8import fsPromises__default, { readFile, mkdir, writeFile, chmod } from 'node:fs/promises'; L9: import require$$0, { execFileSync, ChildProcess, execFile, spawnSync, spawn } from 'node:child_process'; L10: import { createServer } from 'node:http'; L11: import require$$4, { styleText, debuglog, stripVTControlCharacters, inspect, promisify, callbackify, aborted } from 'node:util'; L12: import process$2, { stdout, stdin, platform, hrtime, execPath, execArgv } from 'node:process'; L13: import * as l from 'node:readline'; ... L86: // with no body, we should not to set Content-Type L87: serializedBody === void 0 || // if serialized body is FormData; browser will correctly set Content-Type & boundary expression L88: serializedBody instanceof FormData ? {} : { ... L214: if (parseAs === "json" &

Critical

Hardcoded Runtime Data Exfiltration

Source sends credentials or rich application records to a package-controlled external receiver enabled by default.

dist/index.jsView on unpkg · L8

8Trigger-reachable chain: manifest.main -> dist/index.js L8: import fsPromises__default, { readFile, mkdir, writeFile, chmod } from 'node:fs/promises'; L9: import require$$0, { execFileSync, ChildProcess, execFile, spawnSync, spawn } from 'node:child_process'; L10: import { createServer } from 'node:http'; L11: import require$$4, { styleText, debuglog, stripVTControlCharacters, inspect, promisify, callbackify, aborted } from 'node:util'; L12: import process$2, { stdout, stdin, platform, hrtime, execPath, execArgv } from 'node:process'; L13: import * as l from 'node:readline'; ... L86: // with no body, we should not to set Content-Type L87: serializedBody === void 0 || // if serialized body is FormData; browser will correctly set Content-Type & boundary expression L88: serializedBody instanc

Findings

2 Critical7 High3 Medium5 Low

CriticalHardcoded Runtime Data Exfiltrationdist/index.js

CriticalTrigger Reachable Dangerous Capabilitydist/index.js

HighChild Processdist/index.js

HighShelldist/index.js

HighSame File Env Network Executiondist/index.js

HighCredential Redirect Persistencedist/index.js

HighCommand Output Exfiltrationdist/index.js

HighSandbox Evasion Gated Capabilitydist/index.js

HighTrigger Reachable Command Output Exfiltrationdist/index.js

MediumNetwork

MediumEnvironment Vars

MediumStructural Risk Force Deep Review

LowScripts Present

Affected versions and remediation

This report applies to create-mastra@1.28.0.

See all versions of create-mastra for other recorded verdicts.

Review the evidence and your use of create-mastra@1.28.0 before allowing it. Restrict the permissions described in this report.
Choose an independently verified alternative or release. This report does not establish that other versions are safe.

Evidence last updated: 2026-09-13 00:51:00.754Z (UTC).

Think this verdict is wrong? Dispute it on GitHub or read how reports are produced.

AI Security Review

Decision evidence

Source & flagged code

Source & flagged code

Findings

Affected versions and remediation

Runtime surface

Behavioral surface

Source & flagged code