Prompt Injection

Prompt injection is an attack where malicious instructions embedded in external content — web pages, documents, tool outputs — override or subvert the legitimate instructions given in a system prompt. In agentic systems with tool use and web browsing, prompt injection is a significant security threat: a webpage the agent retrieves might instruct it to exfiltrate data or take unintended actions. Defenses include input sanitization, clear structural separation between instructions and untrusted content, and output validation layers.