AINeutralarXiv – CS AI · Apr 107/10
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The Defense Trilemma: Why Prompt Injection Defense Wrappers Fail?
Researchers prove mathematically that no continuous input-preprocessing defense can simultaneously maintain utility, preserve model functionality, and guarantee safety against prompt injection attacks in language models with connected prompt spaces. The findings establish a fundamental trilemma showing that defenses must inevitably fail at some threshold inputs, with results verified in Lean 4 and validated empirically across three LLMs.