Prompt Injection in 2026: Still OWASP's Number One LLM Vulnerability

Originally published at kunalganglani.com — read it there for inline code, hero image, and live links. Prompt injection is a class of attack where crafted inputs manipulate a large language model into ignoring its instructions, leaking data, or performing unauthorized actions. It has held the #1 position — LLM01 — on OWASP's Top 10 for LLM Applications across every published edition, from the original 2023/24 list through the 2025 update. No other LLM vulnerability has pulled that off. And now...