Brief

Researchers have identified a new vulnerability in large reasoning models (LRMs) called "Chain-of-Thought Hijacking." This attack exploits extended reasoning processes to weaken a model's refusal capabilities, leading to harmful compliance. The method achieves high success rates across several prominent models, including Gemini 2.5 Pro, ChatGPT o4 Mini, Grok 3 Mini, and Claude 4 Sonnet. Analysis suggests that prolonged benign reasoning dilutes safety signals and attention away from harmful intentions, creating a new attack surface. AI