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Rule Reference

SEC492lintai-ai-securitypreviewclaude_settingswarn

Claude settings: shared npm exec Bash permissions

Claude settings permissions allow `Bash(npm exec ...)` in a shared committed config

Provider
lintai-ai-security
Surface
claude_settings
Scope
per_file
Tier
preview
Severity
warn
Confidence
high
Detection
structural
Remediation
message_only

Activation Model

Preset Membership

This rule is part of the builtin activation graph through these preset memberships.

previewmembership
claudemembership

Lifecycle

Stable Lifecycle Contract

State

stable_gated

Graduation rationale

Checks shared committed Claude settings for exact `Bash(npm exec ...)` mutable package-runner authority.

Deterministic signal basis

ClaudeSettingsSignals exact permission detection for `Bash(npm exec ...)` entries inside permissions.allow.

Malicious corpus
claude-settings-npm-exec-bunx-permissions
Benign corpus
claude-settings-npm-exec-bunx-specific-safe
structured evidence required remediation reviewed
Canonical note

Structural preview rule; deterministic today, but the preview contract may still evolve.

Nearby Signals

Related Rules

SEC361Claude settings: missing `$schema`Claude settings file is missing a top-level `$schema` referenceclaude_settingspreview
SEC363Claude settings: home-directory hook pathClaude settings hook command uses a home-directory path in a shared committed configclaude_settingspreview
SEC365Claude settings: non-HTTPS allowed HTTP hook URLClaude settings allow non-HTTPS HTTP hook URLs in a shared committed configclaude_settingspreview
SEC366Claude settings: dangerous HTTP hook host literalClaude settings allow dangerous host literals in `allowedHttpHookUrls`claude_settingspreview
SEC368Claude settings: repo-external absolute hook pathClaude settings hook command uses a repo-external absolute path in a shared committed configclaude_settingspreview
SEC381Claude settings: command hook missing `timeout`Claude settings command hook should set `timeout` in a shared committed configclaude_settingspreview

SEC492 / CLAUDE-NPM-EXEC-PERMISSION ​

SEC492 flags shared Claude settings when permissions.allow grants Bash(npm exec ...).

Why It Matters ​

npm exec resolves and runs packages on demand. Putting that authority into shared Claude settings creates a mutable package-execution path for every user of the config.

Trigger Shape ​

The rule triggers only when all of these are true:

  • the file is a detected Claude settings surface
  • the path is not fixture-like
  • permissions.allow contains a string that starts with Bash(npm exec

Clean Cases ​

These stay clean:

  • non-exec commands such as Bash(npm run lint)
  • settings without Bash(npm exec ...)
  • fixture-like examples under test or fixture paths

Example Trigger ​

json
{
  "permissions": {
    "allow": ["Bash(npm exec eslint:*)", "Read(*)"]
  }
}

Safer Example ​

json
{
  "permissions": {
    "allow": ["Bash(npm run lint)", "Read(*)"]
  }
}

How To Fix ​

Replace shared Bash(npm exec ...) permissions with a pinned wrapper or a narrower reviewed command permission that does not grant mutable package execution by default.