Turn-Based Structural Triggers: Prompt-Free Backdoors in Multi-Turn LLMs

ArXi:2601.14340v2 Announce Type: replace-cross Large Language Models (LLMs) are widely integrated into interactive systems such as dialogue agents and task-oriented assistants. This growing ecosystem also raises supply-chain risks, where adversaries can distribute poisoned models that degrade downstream reliability and user trust. Existing backdoor attacks and defenses are largely prompt-centric, focusing on user-visible triggers while overlooking structural signals in multi-turn conversations.