Researchers show reasoning LLMs can be forced to 'overthink'

At ICML 2026, researchers from Zhejiang University and Alibaba showed they could deliberately trigger excessive 'overthinking' in reasoning large language models (LLMs) using logically inconsistent prompts. The induced reasoning chains act like a denial-of-service vulnerability, slowing models down without improving answer quality.

Why it matters: It highlights a new class of security risk specific to chain-of-thought reasoning models.