Seven Cross-Domain Techniques for Prompt Injection Detection Beyond Pattern Matching

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A new paper argues that both regex-based and fine-tuned transformer classifiers for prompt injection share critical failure modes — regex misses paraphrased attacks, and classifiers are bypassed at >50% success rates by adaptive adversaries (per a 2025 NAACL study). The paper proposes seven cross-domain detection techniques drawn from fields outside NLP to address these gaps. Directly actionable for anyone building agent pipelines that process untrusted input.