How to Prevent Prompt Injection: Why Pre-LLM Sanitization Matters

TL;DR — Prompt Injection Prevention in LLM Applications: Examples and Fixes Prompt injection isn't a model problem — it's an input validation problem. LLMs don't separate instructions from data. Your code has to. Pre-LLM Sanitization is the practice of filtering, validating, and transforming user input before it reaches the LLM — preventing prompt injection and PII leakage at the source. Regex-based filters are easily bypassed. Durable LLM security requires code-level static analysis, not jus...