AI SECURITYLABS

Security for Cursor Development: Check a repository before you trust it

Part 11 of 16

Check a repository before you trust it

A project’s sandbox.json takes priority over yours, its permissions.json is concatenated with yours, and its hooks run once the folder is trusted. Before trusting a repository you didn’t create:

  • Read every JSON file in .cursor/ and stop at anything that widens the sandbox, allowlists commands, or starts a server or command you didn’t write.
  • Read .cursor/rules/, .cursorrules, AGENTS.md and CLAUDE.md, and check them for hidden Unicode.
  • Re-clone repositories that arrived as archives or shared folders, since only those carry their own .git/config, and list every symlink and its target.
  • Don’t rely on .cursorignore: Cursor calls it “not a security boundary” (Cursor docs).