LOS ANGELES (AP) — The University of California is warning students and staff that a ransomware group might have stolen and published their personal data and that of hundreds of other schools, government agencies and companies nationwide. The school this week said a cybersecurity attack targeted a vulnerability in a third-party vendor that is used to securely transfer files. The university system on Friday said the cyberattack affected about 300 organizations. They have included Stanford University’s School of Medicine, Yeshiva University in New York City, university systems in Miami, Maryland and Colorado, and a Washington state agency.