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A learned per-head attention gate cut black-box prompt-injection attack success from 97% to 10% on GPT-OSS-20B by separating instructions from untrusted data inside the model

AspireAI community · arXiv
Heads of Security, an arXiv paper submitted October 27, 2026, proposes enforcing instruction-data separation inside the model through a small set of learned per-head attention gates that redistribute attention between trusted and untrusted tokens so a model can reason over untrusted content without following instructions embedded in it. Evaluated on Llama-3.3-70B-Instruct and GPT-OSS-20B against the finetuning-based SecAlign++ and the architectural ASIDE, the authors report that the black-box RL-Hammer attack reaches 97% attack success rate against GPT-OSS-20B and 85% against SecAlign but only 10% against the gated model, while the white-box Claudini attack needed three times more FLOPs to reach the same attack success rate against the gated model. The gated model also preserved base-model utility on standard multiple-choice benchmarks where SecAlign and ASIDE degraded in few-shot settings, whereas ASIDE collapsed to 10% utility on tool use. The limitation is that this is an architectural modification requiring trained gates, evaluated on two model families and specific attack suites, so it is not a drop-in protection for an existing deployment.
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One distance function matched sparse-autoencoder features across layers and compressed feature circuits into supernodes
Two sparse-autoencoder analyses have resisted scaling: matching semantically similar features across layers, and compressing large feature circuits into interpretable supernodes. This paper argues both are the same underlying problem, estimating semantic distances between SAE features that sit on different activation manifolds. Its representation treats each feature not as a single decoder vector but as an activation-weighted distribution over the hidden states expressing it, projects those distributions into a shared reference space, and compares them with Wasserstein distance. The representation is proved invariant to activation rescaling and stable under perturbation, and recovers true matches under finite-sample margin conditions. Empirically it outperformed decoder-vector and LLM-based baselines and captured subtle functional distinctions between related features, and it compressed large feature circuits into interpretable supernodes automatically. The limitation is that this is interpretability tooling: the paper demonstrates better feature matching and circuit compression, not that downstream interpretability claims become more accurate.
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