The attack vector that OWASP just added to the Top 10 for Agentic Applications — and how to defend against it in 3 lines of Python. If you're building AI agents with persistent memory — using LangChain's MemorySaver , Redis, Chroma, or any other memory backend — there is a class of attack you probably haven't defended against yet. It's called memory poisoning , and it was just codified as ASI06 in the OWASP Top 10 for Agentic Applications . What is memory poisoning? An agent with persistent memory reads from its memory store at the start of every session. If an attacker can write a malicious entry into that store — through a compromised tool output, an injected document, or a direct write — the agent will act on that false information in every future session. The attack is silent. There's no error. The agent behaves normally, except it's now operating on corrupted beliefs. Example: # An attacker writes this to your agent's memory store memory .…