Poison Once, Exploit Forever: Environment-Injected Memory Poisoning Attacks on Web Agents

📰 ArXiv cs.AI

Researchers introduce a new threat model for LLM-based web agents, where environmental observations can contaminate memory, enabling persistent attacks across websites and sessions

advanced Published 6 Apr 2026
Action Steps
  1. Understand the concept of environment-injected memory poisoning attacks
  2. Recognize how LLM-based web agents' memory storage can be contaminated through environmental observations
  3. Develop strategies to mitigate these attacks, such as implementing secure memory storage and access controls
  4. Analyze the potential impact of these attacks on web agent security and develop countermeasures
Who Needs to Know This

Security researchers and AI engineers on a team benefit from understanding this new threat model to develop more robust security measures for LLM-based web agents, as it highlights a previously overlooked vulnerability

Key Insight

💡 Environmental observations can contaminate LLM-based web agents' memory, enabling persistent attacks

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🚨 New threat model: Environment-injected memory poisoning attacks on LLM-based web agents 🚨

Key Takeaways

Researchers introduce a new threat model for LLM-based web agents, where environmental observations can contaminate memory, enabling persistent attacks across websites and sessions

Full Article

Title: Poison Once, Exploit Forever: Environment-Injected Memory Poisoning Attacks on Web Agents

Abstract:
arXiv:2604.02623v1 Announce Type: cross Abstract: Memory makes LLM-based web agents personalized, powerful, yet exploitable. By storing past interactions to personalize future tasks, agents inadvertently create a persistent attack surface that spans websites and sessions. While existing security research on memory assumes attackers can directly inject into memory storage or exploit shared memory across users, we present a more realistic threat model: contamination through environmental observati
Read full paper → ← Back to Reads

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