Analysis
ASCII Smuggling Explained: How Hackers Hide Malicious Prompts in Plain Sight | by Tanmay | Tech Writer
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Why it matters
ASCII smuggling exploits a blind spot in LLM security where hidden characters let attackers slip malicious prompts past human review and keyword filters, making it a stealthy prompt-injection vector defenders must account for.
An explainer by Tanmay describes ASCII smuggling (also called Unicode smuggling), a technique where attackers embed non-printable, invisible, or visually identical characters into ordinary-looking text so that AI agents processing it read hidden malicious instructions invisible to human reviewers. The article frames it as a form of digital steganography exploiting the gap between how humans read text and how LLMs tokenize it, enabling prompt injection that can bypass guardrails or leak system instructions.