The FBI and the US cyber agency CISA have warned that hackers are actively targeting industrial refrigeration and cold-chain monitoring systems — a wider alert than the single French blood-service incident reported earlier this week. The joint advisory, published on 5 November with the US departments of health, agriculture and transport, says attackers are exploiting weaknesses in unpatched or internet-accessible electronic temperature controllers and commercial refrigeration systems.

What the attackers can do

If the attacks succeed, the agencies say, intruders can change temperature settings and force equipment into continuous heating or defrost cycles. That can spoil food, damage equipment and, in the worst cases, create a fire hazard. The named attack routes are authentication bypass flaws, arbitrary code injection and weak configurations.

"Every organization that depends on refrigeration and monitoring systems should assume it could be a target," said Chris Butera, CISA's acting executive assistant director for cybersecurity.

A wave of attacks across Europe

In October, hackers hit refrigeration controllers at an estimated 250 to 350 French supermarkets, remotely switching on defrost functions and raising temperatures. A second wave in November affected more than 115 stores across six European countries, with some systems shutting down entirely and others reaching 50°C.

On 3 November, the French Blood Establishment confirmed that an incident affecting a refrigeration equipment provider had altered temperature and defrost settings at three facilities storing blood products. The US military is also investigating freezer failures at around six military commissaries since late August. The agencies have not attributed the attacks to any group, although researchers have broadly linked them to Iran, TechCrunch reports, and US officials reportedly suspect Iran is the likely culprit.

Operators are urged to take refrigeration controls off the public internet, apply patches and change default passwords.

Sources: BleepingComputer, FBI, CISA warn of cyberattacks targeting refrigeration systems, 5 November 2026; TechCrunch, US government warns of ongoing cyber threat amid mass hacks of industrial, retail and military freezers, 5 November 2026; The Register, Feds warn grocers, 5 November 2026; Joint advisory, CISA/FBI/HHS/USDA/DOT, 5 November 2026.