Ignore All Previous Instructions: A Dev's Guide to Prompt Injection

Prompt injection is the top vulnerability in OWASP's LLM Top 10, and it works by slipping untrusted text into an LLM's context window so it's treated as instructions. Real-world attacks have manipulated car dealership chatbots and bypassed AI email security scanners. Defense requires architectural discipline: separating untrusted input, enforcing least-privilege API access, and adding human-in-the-loop for high-stakes actions.