Indirect Prompt Injection (IPI) is a significant vulnerability in modern AI systems, where attackers embed hidden instructions in data sources that AI models consume, such as webpages, PDFs, and emails, rather than directly interacting with the models through visible prompts. IPI exploits the AI's tendency to treat all ingested text as meaningful, which can lead to unintended actions, data leaks, or system compromises, especially when models are integrated with agentic capabilities that allow them to browse, retrieve, write, or execute tasks. The challenge in mitigating IPI lies in the inherent architectural design of AI systems, which blend trusted and untrusted inputs into a single context stream, making it difficult for models to distinguish between legitimate instructions and malicious ones. Effective mitigation requires a systems-level approach, including implementing trust boundaries, context isolation, output verification, and strict validation of tool interactions. By treating all external data as untrusted and reinforcing these defenses, organizations can better protect against the evolving threat posed by IPI, which continues to escalate as AI systems become more autonomous and integrated with external content.