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This paper introduces a novel multi-turn jailbreaking method, "Intention Deception," that exploits the vulnerability of frontier language models (including GPT-5-thinking and Claude-Sonnet-4.5) to deceptively benign intentions in multi-turn conversations. The method builds conversational trust by simulating benign intentions and exploiting model consistency, ultimately guiding the model toward harmful outputs. The authors also uncover and address a new class of vulnerability called "para-jailbreaking," where the model reveals harmful information indirectly, even if it doesn't directly reply harmfully to the attack query.
Even frontier models like GPT-5 and Claude are highly susceptible to multi-turn jailbreaks that exploit their reliance on inferred user intent, and can even leak harmful information indirectly through "para-jailbreaking."
Large (vision-)language models exhibit remarkable capability but remain highly susceptible to jailbreaking. Existing safety training approaches aim to have the model learn a refusal boundary between safe and unsafe, based on the user's intent. It has been found that this binary training regime often leads to brittleness, since the user intent cannot reliably be evaluated, especially if the attacker obfuscates their intent, and also makes the system seem unhelpful. In response, frontier models, such as GPT-5, have shifted from refusal-based safeguards to safe completion, that aims to maximize helpfulness while obeying safety constraints. However, safe completion could be exploited when a user pretends their intention is benign. Specifically, this intent inversion would be effective in multi-turn conversation, where the attacker has multiple opportunities to reinforce their deceptively benign intent. In this work, we introduce a novel multi-turn jailbreaking method that exploits this vulnerability. Our approach gradually builds conversational trust by simulating benign-seeming intentions and by exploiting the consistency property of the model, ultimately guiding the target model toward harmful, detailed outputs. Most crucially, our approach also uncovered an additional class of model vulnerability that we call para-jailbreaking that has been unnoticed up to now. Para-jailbreaking describes the situation where the model may not reveal harmful direct reply to the attack query, however the information that it reveals is nevertheless harmful. Our contributions are threefold. First, it achieves high success rates against frontier models including GPT-5-thinking and Claude-Sonnet-4.5. Second, our approach revealed and addressed para-jailbreaking harmful output. Third, experiments on multimodal VLM models showed that our approach outperformed state-of-the-art models.