Sandboxing in Claude Code: Permissions, File Access, and Safety Limits

What the Sandbox Means

Claude Code runs with scoped file system permissions by default. It can read files in your project directory and write to locations you explicitly allow. It cannot execute arbitrary commands outside of explicit tool calls, and it cannot access system directories, credentials stores, or other users' home directories.

The sandbox is not a hard security boundary against a malicious actor with full API access — it is a behavior constraint for normal use. Treat it as guard rails, not a security perimeter.

Configuring Permissions

Permissions are set in claude_settings.json:

{
  "permissions": {
    "allow": ["./src/**", "./tests/**"],
    "deny": ["./.env", "./secrets/**"]
  }
}

Claude Code will refuse to read or write files outside the allowed paths. If you need to expand access to new directories, update the config and restart your session.

Command Execution

Claude Code can run shell commands through its tool interface. Commands run under your user context with your environment variables. By default, it cannot run commands that require sudo or interact with system directories.

For CI/CD use, you can expand permissions to allow CI/CD tool access:

{
  "permissions": {
    "allow": ["./src/**", "./tests/**", "./scripts/**"],
    "deny": ["./.env"],
    "allowCommand": ["./scripts/*.sh"]
  }
}

When to Relax Restrictions

For personal projects on your local machine, minimal sandboxing is fine — the risk is yours. For team environments, tighter permissions make sense. For CI/CD, scope permissions to exactly what the pipeline needs.

The key is matching the permission model to the risk profile of the environment.