[Claude Code] Deny .env and credential file access by default

@dani_avila7 If you use Claude Code, you should know this. Claude Code can read your files — including .env files with API keys, database passwords, and third-party service tokens. By default. Daniel San just shared the one-line fix: add explicit permissions in .claude/settings.json to deny env file read/write access. This is a 10-second change that every Claude Code user should make. And it reveals a broader question about how AI agents interact with local filesystems. The specific issue: .env files are the standard way developers store sensitive credentials — API keys for Stripe, AWS, OpenAI, databases, third-party services. They're typically not committed to git. They live locally as plaintext, accessed by applications at runtime. When you run Claude Code in a project directory, Claude can read those files. If you ask Claude to help debug an issue and the context requires understanding your environment, Claude might read your .env to see what's configured. Most of the time this is fine and expected. But if the AI's context later includes generating content that gets shared, logged, or transmitted, your credentials could leak in ways you didn't anticipate. The fix Daniel shared: ``` "permissions": { "deny": [ "Read(**/.env)", "Write(**/.env)", "Edit(**/.env)" ] } ``` Three lines. Blocks all read, write, and edit access to .env files anywhere in the project tree. Claude can still work on your code without seeing credentials. Additional recommendations for Claude Code users: 1. Deny access to .env.local, .env.production, and other environment-specific variants. The pattern `**/.env*` catches all of them. 2. Deny access to .aws/credentials, .kube/config, and other common credential storage locations. 3. Deny access to ~/.ssh/ directory contents. SSH keys should never be in Claude's context. 4. Use git-ignored patterns in your .claude/settings.json — if it's gitignored for a reason, it's usually a file Claude shouldn't read either. For the broader AI agent security conversation: Agents with filesystem access need explicit permission models, not implicit ones. The default for most AI tools has been "access to everything the user can access." That was fine for text generation and research tasks. It's not fine for agents that execute code, modify files, and integrate with sensitive systems. Claude Code does provide explicit permission controls. Most users don't use them. That's a gap between the available security tooling and the default security posture. Every Claude Code user should spend 5 minutes setting up appropriate permissions for their workflow. It's the same discipline as setting up firewall rules — a one-time investment that prevents a category of future problems. For the Claude Code product team: Defaults matter. Most users won't change defaults. Consider whether .env and credential file denial should be in default settings rather than opt-in. The security case is clear. The developer productivity cost is minimal. For the Vercel breach from earlier today: This is the same category of concern from a different direction. Vercel breached means deployed credentials might be exposed. Claude Code reading .env files means local credentials might be logged. Both are variations of "credential handling in AI-integrated developer workflows" that need better defaults. Security practices haven't caught up with AI-integrated development workflows. Individual developers should patch their own workflows while the industry catches up. Follow for practical coverage of AI developer tooling that names the security gaps most content glosses over.