Why Cursor's CORS Fix Opens Your API to Any Website (CWE-942)

Short summary

AI tools like Cursor frequently generate unsafe CORS configurations by reflecting origins combined with credentials enabled, which allows any website to make authenticated requests as your users. This happens because training data emphasizes localhost patterns, CORS errors are loud while vulnerabilities are silent, and most developers can't review the fix safely. Use an explicit allowlist of allowed origins—five lines of code prevent the entire attack.

• •AI tools often auto-generate vulnerable CORS code that reflects origins with credentials, enabling session hijacking attacks
• •Vulnerable patterns are silent (tests pass), while safe versions are visible errors, so AI optimizes for the wrong signal
• •Use explicit origin allowlists instead of wildcards or reflection—five lines of code solve CWE-942 completely

Generated with AI, which can make mistakes.