Problem

vercel env pull writes managed .env* files without explicitly restricting file permissions. On POSIX systems that commonly lands as group/world-readable depending on umask, which is not a great default for secrets downloaded by the CLI.

Root cause

The command writes env files with outputFile(fullPath, contents, 'utf8') and never reapplies a restricted mode after writing.

Fix

• add a small helper that writes managed env files with mode: 0o600
• on POSIX, follow the write with chmod(0o600) so already-existing CLI-managed files are hardened too
• add focused unit tests covering the restricted write options and the POSIX chmod path
• add a changeset for vercel

Solution sketch

flowchart TD
    A[env pull downloads secrets] --> B[write managed env file]
    B --> C[set mode 0o600 on create]
    C --> D{POSIX platform?}
    D -- no --> E[finish]
    D -- yes --> F[chmod file to 0o600]
    F --> E

Duplicate check

• checked adjacent open work like #16312 and #16136; they touch nearby CLI surface but not this permission hardening behavior
• did not find an open issue/PR specifically for restricting env pull output file mode to 0600

Tests

Attempted:

• corepack pnpm test test/unit/commands/env/pull.test.ts

Environment note:

• the local workspace does not have node_modules, so vitest is not available in this environment and the test command could not complete here

Added focused test coverage in:

• packages/cli/test/unit/commands/env/pull.test.ts

Risk

Low. The change only affects files created or rewritten by env pull, and the intent matches existing secure defaults already used elsewhere for sensitive CLI material.