Open-weight artificial-intelligence models — those with publicly available parameters — are becoming essential scientific infrastructure (Y. Gal and S. Casper Nature 646, 286–287; 2025). They broaden access, accelerate replication and enable independent testing. But they also pose a risk: once downloaded, parameters can be modified and safeguards removed. This makes it harder to prevent and trace misuse than in monitored, hosted systems.
Competing Interests
The authors declare no competing interests.
