Context-Aware Prompt Injection Detection via Small Language Models in RAG Pipelines: nokast-secureRAG

Summary

nokast-secureRAG is a roughly 0.5B-parameter small language model that acts as a semantic firewall between retrieval and generation in local RAG systems, classifying each query and retrieved context pair as safe, suspicious, or malicious. On a held-out in-distribution test set it reaches 0.994 detection recall at a 0.026 false-positive rate, but recall falls to near zero on the external PoisonedRAG benchmark, which the authors attribute to fluent fact-poisoning attacks lying outside the detector's instruction-consistency threat model.

Topics

• Prompt injection and jailbreaks
• Retrieval-augmented generation

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