Memory Poisoning: The Silent Threat to AI Agents (and How to Defend Against It)

The Problem Nobody's Talking About

If you're building AI agents with persistent memory — using Mem0, ChromaDB, Pinecone, or custom vector stores — there's a class of attack you need to understand: memory poisoning.

Unlike prompt injection (which resets each session), a poisoned memory entry persists indefinitely. Once an adversary gets a malicious instruction into your agent's memory store, it influences every future interaction.

How the Attack Works

Here's a concrete example: