Large Language Models (LLMs) used as safety judges are vulnerable to an "Emoji Attack," a prompt injection technique that leverages token segmentation bias. Inserting emojis within tokens alters sub-token embeddings, misleading the judge LLM into classifying harmful content as safe. The attack's effectiveness is amplified by strategically placing emojis to maximize the embedding discrepancy between sub-tokens and the original token.
Source: arXiv