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Glossary

Context Window Poisoning

Reviewed 9 April 2026 Canonical definition

Context window poisoning is an attack in which malicious content is injected into an agent's input context — through a retrieved document, a tool response, or a prior conversation turn — with the intent of overriding the agent's instructions or causing it to take harmful actions. It is a variant of indirect prompt injection that targets the context assembly layer rather than the system prompt directly.