The U.S. government has issued an alert over a persistent cyber threat targeting industrial refrigeration systems, which has affected supermarket freezers, military facilities, and at least one blood bank. Agencies including CISA, the FBI, and several federal departments released a joint statement on November 5, 2026, warning that these attacks compromise internet-connected refrigeration and cold chain monitoring systems critical to food, transportation, agriculture, and healthcare industries. The hackers’ ability to manipulate temperatures raises concerns about potential physical damage, including fire hazards and significant inventory spoilage.

Recent incidents in Europe and the UK have highlighted the severity of these attacks, where hackers took control of refrigeration units in multiple countries, leaving thawed and ruined food in their wake. Danish refrigeration manufacturer Danfoss was among those affected, with some targeted devices no longer receiving security updates, which heightened their vulnerability. In France, cybercriminals attempted to increase temperatures in blood bank refrigeration units, although the attack was thwarted before any blood supplies were compromised.

The U.S. Department of Defense is investigating similar disruptions involving military freezer units, with reports first surfacing through independent outlets like Signal and Silence. While no formal attribution has been made, security experts and U.S. officials suspect Iran's involvement in orchestrating these cyberattacks. The broad impact across vital infrastructure has prompted increased vigilance from government agencies and the private sector alike.

Authorities urge organizations managing industrial refrigeration to disconnect affected systems from the internet, strengthen credentials, apply security patches, and retire unsupported equipment. A separate guidance document warned that hackers might force continuous heating or defrost cycles, amplifying risks to equipment and inventory loss. Chris Butera, CISA’s acting cybersecurity chief, emphasized that all users reliant on refrigeration and monitoring technologies should consider themselves potential targets in this ongoing threat landscape.