[2603.00131] Thought Virus: Viral Misalignment via Subliminal Prompting in Multi-Agent Systems

Computer Science > Multiagent Systems arXiv:2603.00131 (cs) [Submitted on 23 Feb 2026] Title:Thought Virus: Viral Misalignment via Subliminal Prompting in Multi-Agent Systems Authors:Moritz Weckbecker, Jonas Müller, Ben Hagag, Michael Mulet View a PDF of the paper titled Thought Virus: Viral Misalignment via Subliminal Prompting in Multi-Agent Systems, by Moritz Weckbecker and 2 other authors View PDF HTML (experimental) Abstract:Subliminal prompting is a phenomenon in which language models are biased towards certain concepts or traits through prompting with semantically unrelated tokens. While prior work has examined subliminal prompting in user-LLM interactions, potential bias transfer in multi-agent systems and its associated security implications remain unexplored. In this work, we show that a single subliminally prompted agent can spread a weakening but persisting bias throughout its entire network. We measure this phenomenon across 6 agents using two different topologies, observing that the transferred concept maintains an elevated response rate throughout the network. To exemplify potential misalignment risks, we assess network performance on multiple-choice TruthfulQA, showing that subliminal prompting of a single agent may degrade the truthfulness of other agents. Our findings reveal that subliminal prompting introduces a new attack vector in multi-agent security, with implications for the alignment of such systems. The implementation of all experiments is publicl...