Prompt Injection in Production: The Attack Patterns That Actually Work and How to Stop Them
Prompt injection is the number one vulnerability in the OWASP Top 10 for LLM applications — and the gap between how engineers think it works and how attackers actually exploit it keeps getting wider. A 2024 study tested 36 production LLM-integrated applications and found 31 susceptible. A 2025 red-team found that 100% of published prompt defenses could be bypassed by human attackers given enough attempts.
The hard truth: the naive defenses most teams reach for first — system prompt warnings, keyword filters, output sanitization alone — fail against any attacker who tries more than one approach. What works is architectural: separating privilege, isolating untrusted data, and constraining what an LLM can actually do based on what it has seen.
This post is a field guide for engineers building production systems. No CTF-style toy examples — just the attack patterns causing real incidents and the defense patterns that measurably reduce risk.
