Open-Weight AI Models May Increase Biological Misuse Risks

Assessing Anti-Refusal Tampering, Capability Enhancement, and Publicly Available Uncensored Models

Sunishchal Dev, Casey O. Barkan, Anthony Hakim, Brooke Hollister, Jeffrey Lee, Alyssa Worland, Dawid Maciorowski, Steph Guerra

ResearchPublished Sep 14, 2026

Open-weight LLMs can be freely downloaded and modified, creating benefits but also biosecurity risks. We examine whether frontier open-weight LLMs can be modified for malicious biological purposes. We find that removing an LLM’s safety training is highly feasible, while enhancing an LLM’s biological capabilities is harder. A custom biosecurity evaluation suggests that safety removal alone could aid a realistic threat pathway.

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Dev, Sunishchal, Casey O. Barkan, Anthony Hakim, Brooke Hollister, Jeffrey Lee, Alyssa Worland, Dawid Maciorowski, and Steph Guerra, Open-Weight AI Models May Increase Biological Misuse Risks: Assessing Anti-Refusal Tampering, Capability Enhancement, and Publicly Available Uncensored Models. Santa Monica, CA: RAND Corporation, 2026. https://www.rand.org/pubs/research_reports/RRA5112-1.html.
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