The widespread adoption of Large Language Models (LLMs) has brought increasing attention to their vulnerability to jailbreak attacks, where adversarial prompts are crafted to bypass safety mechanisms and induce harmful responses. While proprietary models such as GPT-4 have undergone extensive safety evaluations, the robustness of recently released open-source models, including the DeepSeek family, remains less well understood despite their rapid integration into real-world LLM applications. This paper presents a systematic evaluation of jailbreak robustness for the DeepSeek-R1 distilled model family, providing a standardized comparison with GPT-3.5 and GPT-4 using the HarmBench benchmark (v1.0). Our evaluation covers seven representative jailbreak strategies across 320 harmful behaviors from the HarmBench text test split, spanning both functional categories and semantic dimensions. The results show that DeepSeek exhibits certain resistance to automated attacks, particularly LLM-guided approaches such as TAP-T (Tree of Attacks with Pruning–Transfer), but remains more vulnerable to prompt-level and manually constructed adversarial attacks. In comparison, GPT-4 Turbo demonstrates stronger and more consistent safety alignment across diverse harmful behaviors, suggesting the benefit of more extensive safety optimization and reinforcement learning from human feedback. Beyond aggregate attack success rates, our behavioral analysis and case studies reveal that DeepSeek does not consistently enforce safety constraints under adversarial conditions, resulting in irregular refusal patterns across different attack settings. These findings expose a broader challenge in balancing model capability with alignment robustness and motivate the development of more targeted safety tuning techniques for reliable deployment of open-source LLMs.



